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Fuerzas y Túnel 2014

San Sebastián, August 27-29, 2014 I

Introduction

Welcome to the Fuerzas y Túnel 2014 conference (FyT2014) and to San Sebastian. This is the 9th edition of a series of conferences that began in Barcelona in 1998 with the aim to bring together scientist who share an interest in the applications, the use, the development and the theoretical description of technology based in scanning probes. We have assembled a superb program with dedicated sessions to atomic force microscopy, scanning tunneling microscopy and theory of local probes techniques covering a wide range of applications from soft matter physics and biophysics to surface science in vacuum. We are very gratified by the number and outstanding quality of contributions, from which we have selected more than thirty short talks. We are pleased to be hosting three invited lectures of experts on AFM and STM.

Importantly, Prof. Arturo M. Baró retired this year and we have dedicated a session to honor his extensive and inspiring career pioneering scanning probe techniques in Spain. Four invited speakers will talk about Arturo´s scientific life from an informal and relaxed point of view.

Finally, the conference will be held at the Palacio Miramar at the city center of San Sebastian. The location of this fantastic royal palace could not be better: right between "La Concha" and "Ondarreta" beaches offering a splendid view over the bay and the city. We hope that you will find time to explore and enjoy the city of San Sebastian and to join us in the conference dinner at the typical basque "sidreria" with plenty to drink and to eat.

Enjoy the meeting!

With best wishes,

Fernando and Celia, the organizers

II Fuerzas y Túnel 2014

Organizers

Celia Rogero [email protected] Centro de Física de Materiales (CSIC-UPV/EHU) Materials Physics Center (MPC) Paseo Manuel de Lardizabal 5 20018 San Sebastian, Spain http://dipc.ehu.es/nanolab

Fernando Moreno-Herrero [email protected] Dept. Macromolecular Structures Lab. B17-B-18 Centro Nacional de Biotecnología (CNB-CSIC) C/ Darwin, 3. 28049, Cantoblanco, Spain www.fernandomorenoherrero.com

Scientific Committee

Andrés Arnau (EHU/UPV) Agustina Asenjo (ICMM) Jaime Colchero (UM) Jordi Fraxedas (CIN2) José Miguel García (IMM) Ricardo García (ICMM) Julio Gómez (UAM) José María Gómez-Rodríguez (UAM) Amadeo López de Parga (UAM) José Angel Martin-Gago (ICMM) Javier Méndez (ICMM) Aitor Mugarza (ICN) Pedro J. de Pablo(UAM) Jose Ignacio Pascual (CIC-Nanogune) Rubén Pérez (UAM) Roberto Otero (UAM) Juan José Saenz (UAM)

Invited Speakers Prof. Dr. Katharina J. Franke, Freie Universität, Berlín http://www.physik.fu-berlin.de/einrichtungen/ag/ag-franke/

Prof. Dr Neil H. Thomson, University of Leeds, Leeds http://www.astbury.leeds.ac.uk/people/staff/staffpage.php?StaffID=NHT

Prof. Dr. Pavel Jelinek, Czech Academy of Science, Praha http://jelinekp.fzu.cz/

Session Tribute to Prof. Arturo M. Baró

Prof. Dr. Christoph Gerber, University of Basel, Switzerland https://physik.unibas.ch/dept/pages/de/personnel/gerber.htm

Prof. Dr Ron Reifenberger, Purdue University, USA http://www.physics.purdue.edu/people/faculty/rr.shtml

Prof. Dr. Arvind Raman, Purdue University, USA https://engineering.purdue.edu/ME/People/ptProfile?id=12884

Prof. Dr. Ignacio Pascual, CIC Nanogune, Spain http://www.nanogune.eu/en/research/nanoimaging/people/jose-ignacio-pascual/

http://dipc.ehu.es/nanolab

http://www.physik.fu-berlin.de/einrichtungen/ag/ag-franke/

http://www.astbury.leeds.ac.uk/people/staff/staffpage.php?StaffID=NHT

http://jelinekp.fzu.cz/

https://physik.unibas.ch/dept/pages/de/personnel/gerber.htm

http://www.physics.purdue.edu/people/faculty/rr.shtml

https://engineering.purdue.edu/ME/People/ptProfile?id=12884

http://www.nanogune.eu/en/research/nanoimaging/people/jose-ignacio-pascual/

San Sebastián, August 27-29, 2014 III

Venue, and key locations map Lectures will take place at the “Palacio Miramar” in San Sebastián, right between "La Concha" and "Ondarreta" beaches (see map below). Conference dinner will be at "Ezeiza" Restaurant. Delegates residence "Agud Querol", Materials Physics Center, and Donosti International Physics Center sites can also be located in the following map.

Participant Information

Registration

The registration desk will open on Tuesday 26 August from 16:00 to 19:00 at the Residence Agud Querol and on Wednesday 27 August from 8:00 to 9:00 and it will be located at Palacio de Miramar.

2014 FyT SPM Image Contest

Bring your best SPM-based image to the Registration Desk on the 27th August or hand it to the organizers to be part of this exiting competition. There will be a very generous prize sponsored by Bihurcrystal for the best image selected by voting of all delegates.

Poster Session

Posters can be hanged from Wednesday to Friday. There will be a unique session where delegates are requested to be presenting their posters. However, poster viewing can be done over the entire duration of the conference.

Official Presenting time: Thrusday 28 August 2014, from 17:50-20:00.

Poster Prize

Two poster prizes will be awarded to the best posters presented at this conference by a researcher in the early stages of their career (post graduate or first postdoctoral position).

IV Fuerzas y Túnel 2014

Oral Communications

Oral communications will be given in the Lecture Theater. Please refer to the Scientific Programme for timings.

A PC computer will be available for speakers bringing a USB stick with their talk. We encourage the use of PowerPoint for their presentations. Alternatively, you may use your own laptop if desired. If you are bringing a Mac, please remember to bring the necessary adaptors to plug into a standard projector connection.

Speakers are requested to check their presentations with the chair of their session well in advance the begining of their presenting session.

Speakers are requested to adjust to the time allocated for their talk of presentation. Session Chairs have been told to be strict on times.

Facilities Information

Accommodation

Residencia Manuel Agud Querol. It is five minutes from the Lecture Hall: http://www.resa.es/Residencias/Manuel-Agud-Querol

Further Information

Science for the General Public Event

In the context of science disemination for the general public, José Angel Martín Gago (ICMM, CSIC) will talk about "El origen de la vida desde la nanociencia " at the Sala de Actos Kutxa Andia (c/Andia s/n) on August, Tuesday 26th at 19:30h.

Certificates of Attendance

A Certificate of Attendance will be issue upon request. Attendees requiring a Certificate of Attendance for the conference should contact the organizers or the conference registration desk.

Internet access

Wireless internet access is available at the meeting space. Please go to the registration desk to collect an access code for the wireless network.

How to get to San Sebastian, Spain

By plane:

- Bilbao airport (BIO): About 1 hour drive from San Sebastian. A direct shuttle bus running every hour connects Bilbao airport and San Sebastian for about 17 euros. The bus time table is available at http://www.pesa.net/.

- San Sebastian airport (EAS): 30 minutes drive from San Sebastian. Small airport with domestic connections to Madrid and Barcelona. Iberia flies to this airport. A regular bus connect the airport and the city (time table is available at http://www.lurraldebus.net/). A taxi connecting the airport and the city should be around 30 euros.

http://www.resa.es/Residencias/Manuel-Agud-Querol

http://www.pesa.net/

http://www.lurraldebus.net/

San Sebastián, August 27-29, 2014 V

- Biarritz (BIQ): 40 minutes drive from San Sebastian. Air France flies to this airport, and some low-cost airlines such as Ryanair also fly here. Bus connexion is available from the airport to Donostia. For more information check http://www.conda.es/

By train:

The Adif train station “Estación del Norte” is in the center of San Sebastian, close to Urumea river. It offers connections to several Spanish cities, including Madrid and Barcelona.

There is also Metro Donostialdea, http://www.euskotren.es, popullarly known as “Topo”, a narrow-gauge train connecting Donostia with cities along the Basque Coast, from Bilbao and Hendaye (France).

By bus:

The San Sebastian bus station has lines to cities troughout Spain. The main company traveling here is Alsa http://www.alsa.es/.

By car:

The city is connected to the rest of Spain by the N-1 (Madrid-Irun highway), AP-8 (Bilbao-Irun highway), and A-15 (Pamplona-San Sebastian highway).

http://www.conda.es/

http://www.euskotren.es/

http://www.alsa.es/

San Sebastián, August 27-29, 2014 1

Scientific Programme

Tuesday 26 August 2014

17:00-19:00 Registration

Science for the general public

Sala de Actos Kutxa Andia (c/Andia s/n)

19:30-20:30 El origen de la vida desde la nanociencia José Angel Martín Gago (ICMM-CSIC, Madrid, Spain))

Wednesday 27 August 2014

9:00-9:15 Welcome words. The organizers

Session 1. Magnetism

Session Chair: Agustina Asenjo (ICMM-CSIC, Spain)

9:15-10:00 Manipulation of spin states and magnetic anisotropy of individual metal-organic complexes on surfaces Katharina J. Franke (Freie Universität Berlin, Germany)

10:00-10:20 Magnetic Coupling Of Tm And Lu Adatoms With Fe Monoatomic Islands On W(110): Spin-polarized Tunneling Microscopy And Ab-initio Calculations David Coffey (Universidad de Zaragoza, Spain)

10:20-10:40 Effects Of The Kondo Coupling On Magnetic Adsorbates On Surfaces Fernando Delgado (INL-International Iberian Nanotechnology Laboratory, Braga, Portugal)

10:40-11:00 Magnetic Force Microscopy Imaging In Liquid Pablo Ares (Universidad Autónoma de Madrid, Spain)

11:00-11:20 State Of A Single Molecule By Local Gating On A Semiconductor Surface Jesús Martínez-Blanco (Paul-Drude-Institut für Festkörperelektronik. Berlin, Germany)

11:20-11:40 Vector Mapping Of The Magnetic Moment Of Individual Atoms Using Spin Polarized STM María Moro (Universidad de Zaragoza, Spain)

11:40-12:00 COFFEE BREAK

Session 2. Synthesis on Surfaces

Session Chair: José Ángel Martín Gago (ICMM-CSIC, Spain)

2 Fuerzas y Túnel 2014

12:00-12:20 On-Surface Synthesis Of BN/Graphene Hybrid Structures Carlos Sánchez-Sánchez (Empa, Swiss Federal Laboratories for Materials Science and Technology, Switzerland)

12:20-12:40 Charge-transfer Induced Isomerization Of DCNQI On Cu(100) Roberto Otero (Universidad Autónoma de Madrid, Spain)

12:40-13:00

Theoretical STM Characterization Of On-surface Reactions Of Heteroaromatics José Ignacio Martínez (Instituto de Ciencias de Materiales de Madrid, ICMM, -CSIC, Spain)

13:00-13:20 Customizing Metallocene layers on Cu(111) Maider Ormaza (Institut de Physique et Chimie des Matériaux de Strasbourg, France)

13:20-15:30 LUNCH

Session 3. Graphene and 2D-systems I

Session Chair: Aitor Mugarza (ICN2, Barcelona, Spain)

15:30-15:50 Electron Scattering Of Rashba-split States In The BiAg2 Surface Alloy Stefano Schirone (ICN2 - Institut Catala de Nanociencia i Nanotecnologia, Barcelon, Spain)

15:50-16:10 Graphene tunable electronic tunneling transparency: A unique tool to measure the local coupling Héctor González-Herrero (Universidad Autónoma de Madrid, Spain)

16:10-16:30 Graphene Etching On SiC Grains As A Path To Interstellar Polycyclic Aromatic Hydrocarbons Formation Pablo Merino (Centro de Astrobiología INTA-CSIC, Madrid, Spain)

16:30-16:50 Observation of giant bandgap renormalization and excitonic effects in a monolayer transition metal dichalcogenide semiconductor Miguel Moreno (University of California at Berkeley, USA)

16:50-17:10 Electrostatic Manipulation Of Graphene On Graphite Carmen Rubio (University of Alicante, Spain)


Session Tribute to Prof. Arturo M. Baró

17:30-17:35 Welcome words


17:35-18:05 AFM Technologies in personolized medical diagnostics Christoph Gerber (University of Basel, Switzerland)

18:05-18:35 Looking back 30 years at Baro’s Laboratorio de Nuevas Microscopías: the recollections of a mid-western American Ron Reifenberger (Purdue University, USA)

18:35-19:05 Scanning the trends of Atomic Force Microscopy Arvind Raman (Purdue University, USA)

19:05-19:35 Tunneling Microscopy: Retrospectives and perspectives Ignacio Pascual (CIC Nanogune, Donosti-San Sebastián, Spain)

Thursday 28 August 2014

Session 4. AFM Applications in Biology

Session Chair: Pedro J. de Pablo (Universidad Autónoma de Madrid, Spain)

9:15-10:00 Realising quantitative dynamic atomic force microscopy to probe transactions of DNA at the single molecule level Neil H. Thomson (University of Leeds, UK)

10:00-10:20 Imaging Of Biosystems By Dynamic Atomic Force Microscopy Magali Phaner (Université de Lyon, France)

10:20-10:40 Fast Nanomechanical Spectroscopy of Soft Matter Alma Eva Pérez Perrino (Instituto de Ciencias de Materiales de Madrid, Spain)

10:40-11:00 Mechanical uncoating of a virus genome: an AFM-TIRF combined experiment Alvaro Ortega-Esteban (Universidad Autónoma de Madrid, Spain)

11:00-11:20 Mechanical Properties Of Antibodies As Measured By AFM: An Atomistic Molecular Dynamics Study Gilherme Vilhena (Universidad Autónoma de Madrid, Spain)

11:20-11:40 Structural Analysis Of Individual Protein Complexes By Infrared Scattering At An AFM Tip Iban Amenabar (CIC nanoGUNE, San Sebastián, Spain)


Session 5. Graphene and 2D-systems II

Session Chair: Daniel Sánchez Portal (DIPC, San Sebastián, Spain)

12:00-12:20 Scattering properties of graphene nanostructures on Ni(111)-2 Aran García-Lekue (Donostia International Physics Center (DIPC), Spain)


12:20-12:40 Multidomain graphene on Rh(111)_ STM study of unusual moire patterns Ana Martín-Recio (Universidad Autónoma de Madrid, Spain)

12:40-13:00 Mechanical properties of graphene with defects created by ion bombardment Guillermo López-Polín (Universidad Autónoma de Madrid, Spain)

13:00-13:20 Uniaxial Strain Control of Metal Insulator Transitions in Sr2IrO4 thin films Neus Domingo (ICN2 - Institut Catala de Nanociencia i Nanotecnologia, Bellaterra, Spain)

13:20-15:30 LUNCH

14:30-15:30 Organizing Committee Annual Meeting

Session 6. New Developments and Related Techniques

Session Chair: Jaime Colchero (Universidad de Murcia, Spain)

15:30-15:50 In Situ High Pressure STM Imaging Of A Fischer-Tropsch Cobalt Catalyst Violeta Navarro (Leiden University, The Netherlands)

15:50-16:10 Nanophotoactivity Of Porphyrin Functionalized ZnO Solar Cells

Elisa Palacios-Lidón (Universidad de Murcia, Spain)

16:10-16:30 Study Of Polymer Relaxation Dynamics By Means Of AFM Based Dielectric Spectroscopy Alejandro Miccio (Universidad del País Vasco, San Sebastián, Spain)


16:50-17:10 A single-molecule approach to study dynamics of DNA helicases by applying magnetic forces Carolina Carrasco (Centro Nacional de Biotecnología, Madrid, Spain)

17:10-17:30 XPEEM And LEEM: State Of The Art Surface Characterization Tools At ALBA Lucía Aballe (ALBA Syncroton Light Facility, Barcelona, Spain)

17:30-17:50 Nanoscale IR Spectroscopy, Dielectric Function Mapping And Depth Profiling With Near-field Microscopy Alexander Govyadinov (CIC Nanogune Consolider, San Sebastián, Spain)

17:50-20:00 POSTER SESSION. Sponsored by

20:30 BUS TO CONFERENCE DINNER


Friday 29 August 2014

Session 7. Combined AFM/STM I

Session Chair:

Julio Gómez. (Universidad Autónoma de Madrid, Spain)

10:15-11:00 A step further for better understanding of molecular junctions and highresolution SPM images Pavel Jelinek (Institute of Physics of the AS CR, Prague, Czech Republic)

11:00-11:20 Bandgap Engineering Of Bottom-Up Synthesized Graphene Nanoribbons Dimas de Oteyza (Centro de Física de Materiales, CSIC-UPV/EHU, San Sebastián, Spain)

11:20-11:40 General Force Reconstruction Method for Amplitude Modulation Force Microscopy Experiment Amir Farokh (Instituto de Ciencias de Materiales de Madrid, ICMM-CSIC, Spain)


Session 8. Combined AFM/STM II

Session Chair:

Julio Gómez. (Universidad Autónoma de Madrid, Spain)

12:00-12:20 Adsorption Geometry Of Pentacene On TiO2 Anatase Surface Resolved By Intra-molecular Atomic Force Microscopy Imaging Cesar Moreno (National Institute for Materials Science (NIMS), Tsukuba, Japan)

12:20-12:40 Attractive Tip-sample Force Reconstruction For Dynamic Atomic Force Microscopy In Ambient Conditions Albert Verdaguer (Institut Català de Nanociencia i Nanotecnologia, ICN2, Spain)

12:40-13:00 Atomic Force Microscopy In High Vacuum: Experiments On Graphitic Surfaces Miriam Jaafar (Instituto de Ciencias de Materiales de Madrid, ICMM-CSIC, Spain))

13:00-13:20 Poster and SPM Image Contest Prizes sponsored by

13:20 Final remarks. The organizers


SCIENCE FOR THE GENERAL PUBLIC

Sala de actos Kutxa Andia (c/Andia s/n)


El origen de la vida desde la nanociencia

José Angel Martín Gago

Instituto Ciencia de Materiales de Madrid-CSIC

Entre las preguntas más recurrentes de la humanidad está la que se refiere al origen de la vida en nuestro Planeta. Cómo y de dónde proviene el ser humano es un misterio al que distintas religiones y filosofías se han acercado a lo largo de la historia. Hoy día también la ciencia, utilizando exclusivamente el método científico, se plantea responder a esta pregunta: “¿de dónde venimos? ¿cuál es nuestro origen?”.

En esta presentación intentaremos “rebobinar” la película de la vida en la Tierra, desde nuestro mundo actual, lleno de diversidad, hasta el universo vacío y oscuro. Antes de que se formase nuestro planeta azul sólo había un universo repleto de luz en el que vagaban algunas pequeñas moléculas. Era el reino de la física. Poco a poco esas moléculas se encontraron en el espacio y comenzó a funcionar la química. Después se formaron los planetas (la geología) y con ellos la química antes de la vida. Esa química se fue convirtiendo en bio-química y posteriormente en biología, en vida.

Por otra parte, y curiosamente, este proceso es muy similar al que persigue la nanociencia y la nanotecnología, áreas del conocimiento que se inspiran en la forma de actuar de la naturaleza para construir nuevos dispositivos importantes para el bienestar. La investigación actual sobre el origen de la vida aborda una serie de retos y dificultades. Es una investigación interdisciplinar en la que tanto la falta de datos experimentales como de otros ejemplos conocidos de vida fuera de la Tierra son un lastre importante. En esta presentación se revisarán esos retos; veremos cómo las nuevas tendencias en nanotecnología y el concepto moderno del átomo pueden combinarse para darnos algunas repuestas a este tema tan difícil.


ABSTRACTS. ORAL PRESENTATIONS


List of Oral Presentations by Title

Manipulation of spin states and magnetic anisotropy of individual metal-organic complexes on surfaces....................................... 13

Katharina J. Franke ...................................................................................................................................................................... 13

Magnetic Coupling of Tm and Lu Adatoms with Fe Monoatomic Islands on W(110): Spin-polarized Tunneling Microscopy and Ab-initio Calculations ............................................................................................................................................................................... 14

D. Coffey, J. L. Diez-Ferrer, D. Serrate, M. Ciria, C. de la Fuente, J. I. Arnaudas ...................................................................... 14

Effects Of The Kondo Coupling On Magnetic Adsorbates On Surfaces ........................................................................................... 15

F. Delgado, Joaquín Fernández-Rossier ..................................................................................................................................... 15

Magnetic Force Microscopy Imaging In Liquid .................................................................................................................................. 15

P. Ares, M. Jaafar, A. Gil, J. Gómez-Herrero, A. Asenjo ............................................................................................................. 15

State Of A Single Molecule By Local Gating On A Semiconductor Surface ..................................................................................... 16

Jesús Martínez-Blanco, Christophe Nacci, Kyoshi Kanisawa, Steven Erwin, Stefan Fölsch ...................................................... 16

Vector Mapping Of The Magnetic Moment Of Individual Atoms Using Spin Polarized STM ............................................................ 17

M. Moro, M. Piantek, J. I. Pascual, M. R. Ibarra, D. Serrate ........................................................................................................ 17

On-Surface Synthesis Of BN/Graphene Hybrid Structures ............................................................................................................... 18

Carlos Sanchez-Sanchez, Matthias Müller, Holger F. Bettinger, Sebastian Brüller, Klaus Müllen, Leopold Talirz, Carlo Pignedoli, Pascal Ruffieux, Roman Fasel .................................................................................................................................... 18

Charge-transfer Induced Isomerization Of DCNQI On Cu(100) ........................................................................................................ 19

C. Urban, Y. Wang, J. Rodríguez-Fernández, M. A. Herranz, M. Alcamí, N. Martín, F. Martín, J. M. Gallego, R. Otero, R. Miranda ........................................................................................................................................................................................ 19

Theoretical STM Characterization Of On-surface Reactions Of Heteroaromatics ............................................................................ 20

Jose Ignacio Martinez, Anna Lisa Pinardi, Gonzalo Otero-Irurueta, Maria Francisca Lopez, Javier Mendez, Jose Angel Martin-Gago ............................................................................................................................................................................................. 20

Customizing Metallocene layers on Cu(111) ..................................................................................................................................... 21

Ormaza Maider, Bachellier Nicolas, Bocquet Marie-Laure, Lorente Nicolas, Limot Laurent ....................................................... 21

Electron Scattering Of Rashba-split States In The BiAg2 Surface Alloy ........................................................................................... 21

S. Schirone, R. Piquerel, G. Bihlmayer, E. E. Krasovskii, P. Gambardella, A. Mugarza ............................................................. 21

Graphene tunable electronic tunneling transparency: A unique tool to measure the local coupling ................................................. 23

H. González-Herrero, A.J. Martínez-Galera, M.M. Ugeda, F. Craes, D. Fernández-Torre, P. Pou, R. Pérez, J.M. Gómez-Rodríguez and I. Brihuega............................................................................................................................................................ 23

Graphene Etching On SiC Grains As A Path To Interstellar Polycyclic Aromatic Hydrocarbons Formation .................................... 24

P. Merino, M. Švec, J.I. Martinez, P. Jelinek, P. Lacovig, M. Dalmiglio, S. Lizzit, P. Soukiassian, J. Cernicharo, J.A. Martin-Gago ............................................................................................................................................................................................. 24

Observation Of Giant Bandgap Renormalization And Excitonic Effects In A Monolayer Transition Metal Dichalcogenide Semiconductor ................................................................................................................................................................................... 25

Miguel M. Ugeda, Aaron J. Bradley, Su-Fei Shi, Felipe H. da Jornada, Yi Zhang, Diana Y. Qiu, Sung-Kwan Mo, Zahid Hussain, Zhi-Xun Shen, Feng Wang, Steven G. Louie, Michael F. Crommie ............................................................................................ 25

Electrostatic Manipulation Of Graphene On Graphite ....................................................................................................................... 25

C. Rubio-Verdú, J. Martínez, M.J. Caturla, G. Sáenz-Arce, D. C. Milán, C. Untiedt ................................................................... 25

AFM Technologies in personolized medical diagnostics ................................................................................................................... 26

Christoph Gerber .......................................................................................................................................................................... 26


Looking back 30 years at Baro’s Laboratorio de Nuevas Microscopías: the recollections of a mid-western American .................. 27

Ron Reifenberger ......................................................................................................................................................................... 27

Scanning the trends of Atomic Force Microscopy ............................................................................................................................. 27

Arvind Raman .............................................................................................................................................................................. 27

Tunneling Microscopy: Retrospectives and perspectives.............................................................................. ....................................27

Ignacio Pascual ............................................................................................................................................................................ 27

Realising quantitative dynamic atomic force microscopy to probe transactions of DNA at the single molecule level ...................... 29

Neil H Thomson ........................................................................................................................................................................... 29

Imaging Of Biosystems By Dynamic Atomic Force Microscopy ........................................................................................................ 30

Magali Phaner-Goutorbe .............................................................................................................................................................. 30

Fast Nanomechanical Spectroscopy of Soft Matter .......................................................................................................................... 30

E. T. Herruzo, A.P. Perrino , R. Garcia ........................................................................................................................................ 30

Mechanical uncoating of a virus genome: an AFM-TIRF combined experiment .............................................................................. 31

A. Ortega-Esteban, K. Bodensiek, G. Condezo, M. Suomalainen, U. Greber, C. San Martín, P. J. De Pablo, I. A. T. Schaap . 31

Mechanical Properties Of Antibodies As Measured By AFM: An Atomistic Molecular Dynamics Study .......................................... 32

J.G. Vilhena, Pedro A. Serena, Ruben Perez .............................................................................................................................. 32

Structural Analysis Of Individual Protein Complexes By Infrared Scattering At An AFM Tip ............................................................ 33

Iban Amenabar, Simon Poly, Wiwat Nuansing, Elmar H. Hubrich, Alexander A. Govyadinov, Florian Huth, Roman Krutokhvostov, Lianbing Zhang, Mato Knez, Joachim Heberle, Alexander Bittner, Rainer Hillenbrand ..................................... 33

Scattering Properties Of Graphene Nanostructures On Ni(111) ....................................................................................................... 34

A. Garcia-Lekue, T. Balashov, M. Ollé, G. Ceballos, A. Arnau, P. Gambardella, D. Sánchez-Portal, A. Mugarza ..................... 34

Multidomain graphene on Rh(111): STM study of unusual moiré patterns ....................................................................................... 35

A. Martín-Recio, A. J. Martínez-Galera, J. M. Gómez-Ródriguez ................................................................................................ 35

Mechanical Properties Of Graphene With Defects Created By Ion Bombardment ........................................................................... 36

Guillermo López-Polín, Cristina Gomez-Navarro, Vincenzo Parente, Francisco Guinea, Mikhail I. Katsnelson, Francesc Perez-Murano, Julio Gomez-Herrero...................................................................................................................................................... 36

Uniaxial Strain Control of Metal Insulator Transitions in Sr2IrO4 thin films ........................................................................................ 37

L. López-Mir, X.Martí, M. Paradinas, C.Ocal, G.Catalán, N.Domingo. ........................................................................................ 37

In Situ High Pressure STM Imaging Of A Fischer-Tropsch Cobalt Catalyst ..................................................................................... 38

Violeta Navarro, M.A. van Spronsen, J.W.M. Frenken ................................................................................................................ 38

Nanophotoactivity Of Porphyrin Functionalized ZnO Solar Cells ...................................................................................................... 39

Elisa Palacios-Lidón, David F. Pickup, Eneko Azaceta, Jaime Colchero, Ramón Tena-Zaera, Celia Rogero ........................... 39

Study Of Polymer Relaxation Dynamics By Means Of AFM Based Dielectric Spectroscopy ........................................................... 40

L.A.Miccio, G.A.Schwartz, A.Alegría, J.Colmenero ..................................................................................................................... 40

A single-molecule approach to study dynamics of DNA helicases by applying magnetic forces...................................................... 41

Carolina Carrasco, Neville Gilhooly, Mark S. Dillingham, and Fernando Moreno-Herrero. ......................................................... 41

XPEEM And LEEM: State Of The Art Surface Characterization Tools At ALBA .............................................................................. 42

Lucia Aballe, Michael Foerster ..................................................................................................................................................... 42

Nanoscale IR Spectroscopy, Dielectric Function Mapping And Depth Profiling With Near-field Microscopy ................................... 43

Alexander Govyadinov, Stefan Mastel, Federico Golmar, Andrey Chuvilin, P. Scott Carney, Rainer Hillenbrand ..................... 43


A step further for better understanding of molecular junctions and highresolution SPM images ...................................................... 45

P. Jelinek ...................................................................................................................................................................................... 45

Bandgap Engineering Of Bottom-Up Synthesized Graphene Nanoribbons...................................................................................... 45

Dimas G. de Oteyza, Yenchia Chen, Ting Cao, Chen Chen, Zahra Pedramrazi, Danny Haberer, Felix R. Fischer, Steven G. Louie, Michael F. Crommie .......................................................................................................................................................... 45

General Force Reconstruction Method for Amplitude Modulation Force Microscopy Experiment.................................................... 46

A.F. Payam, D. Martin-Jimenez , R. Garcia ................................................................................................................................. 46

Adsorption Geometry Of Pentacene On TiO2 Anatase Surface Resolved By Intra-molecular Atomic Force Microscopy Imaging . 47

Cesar Moreno, Oleksandr Stetsovych, Milica Todorovic, Tomoko K. Shimizu, Rubén Pérez, Oscar Custance ......................... 47

Attractive Tip-sample Force Reconstruction For Dynamic Atomic Force Microscopy In Ambient Conditions .................................. 48

Albert Verdaguer, Annalisa Calo, Carlo Alberto Amadei, Matteo Chiesa, Sergio Santos ........................................................... 48

Atomic Force Microscopy In High Vacuum: Experiments On Graphitic Surfaces ............................................................................. 49

M. Jaafar, G. López Polin, D. Martínez Martín, C. Gómez Navarro, J. Gómez Herrero .............................................................. 49

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Wednesday, August 27, 2014, San Sebastián, Spain 13

Manipulation of spin states and magnetic anisotropy of individual metal-organic complexes on surfaces

Katharina J. Franke

Fachbereich Physik, Freie Universität Berlin, Berlin, Germany

The magnetic properties of atoms and molecules on a surface are significantly affected by details in the atomic-scale surrounding. Manipulation of this surrounding provides the possibility to tune the electronic and magnetic functionality of surfaces on the nanometer scale. Here, we use scanning tunneling spectroscopy to resolve the magnetic properties of individual paramagnetic metal-organic complexes on normal metal and superconducting surfaces.

We show that the lifetime of excited spin states in the paramagnetic Fe-Octaethylporphyrin-Chloride (FeOEP-Cl) is orders of magnitude longer when the molecule is adsorbed on a superconductor as compared to a normal metal substrate. We ascribe this increase in spin relaxation time to the superconducting energy gap at the Fermi level, which prohibits efficient pathways of energy quenching into the substrate [1]. The small spin relaxation rates allow for pumping into higher spin states by large current densities.

The magnetic anisotropy of the individual molecules can be varied by the proximity of the STM tip. Approaching the STM tip to the molecule leads to a deformation of the molecular ligand field, resulting in an increase in the axial anisotropy.

Removal of the central Cl ligand changes the oxidation and spin state, respectively. The spin excitation spectra reveal a notable axial and transverse anisotropy, which are also affected by the distance of the STM tip.

We further manipulate the magnetic properties of individual FeOEP molecules on a gold surface by an in-situ chemical reaction of the organic ligand. A temperature-induced step-wise electrocyclic ring closure of the ethyl groups results in the final product Fe-Tetrabenzoporphyrin (FeTBP). The chemical modification is accompanied by an increased magnetic interaction with the metallic substrate as resolved by changes in the shape and width of a Kondo resonance [2].

[1]. B. W. Heinrich, L. Braun, J. I. Pascual, K. J. Franke, Nature Physics 9, 765 (2013) [2]. B. W. Heinrich, G. Ahmadi, V. L. Müller, L. Braun, J. I. Pascual, K. J. Franke, NanoLetters 13, 4840

(2013)


Magnetic Coupling of Tm and Lu Adatoms with Fe Monoatomic Islands on W(110): Spin-polarized Tunneling Microscopy and Ab-initio

Calculations

D. Coffey1, J. L. Diez-Ferrer

1, D. Serrate

1, M. Ciria

1, C. de la Fuente

1, J. I. Arnaudas

1

1 Universidad de Zaragoza

In Rare Earth-Transition Metal (RE-TM) compounds the RE-TM magnetic interaction proceeds via an indirect mechanism in which the 5d electrons act as the intermediary.[1] When the 5d band is less than half full and the 3d band is more than half full, the case of RE-(ferromagnetic TM) compounds, the 5d-3d exchange is antiferromagnetic and the RE and TM spins couple antiparallel. Here, we report on an extreme situation, where only adatoms of RE are adsorbed on a TM ferromagnetic monolayer. We have investigated with scanning tunneling microscopy and spectroscopy Thulium and Lutetium adatoms, deposited on iron monolayer islands, with in-plane magnetization [2], pseudomorphically grown on a clean W(110) substrate under ultra-high vacuum conditions, at low temperature. The spin polarized differential conductance images (Fig. 1), obtained with an Fe covered tungsten tip and taken both at constant height and at constant current, show that Tm and Lu present a contrast opposite to the one shown by the respective Fe islands beneath. A possible dependence on the spin polarization shown by the adatom on the energy and vertical distance to the tip [3] has been discarded by performing the measurements at different bias and heights without appreciable modification of the reversed contrast observed between the adatom and the island. First principles calculations show that the Lu and Tm 5d moments lie in plane and couple antiferromagnetically with their underlying iron islands, in agreement with the Campbell model even at the single atom limit.

[1]. I. A. Campbell, J. Phys. F Met. Phys. 2, L47 (1972). [2]. N. Weber et al., Phys. Rev. B 55, 14121 (1997). [3]. N. Néel et al., Phys. Rev. B 85, 155406 (2012).

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Effects Of The Kondo Coupling On Magnetic Adsorbates On Surfaces

F. Delgado1, Joaquín Fernández-Rossier

1

1 INL-International Iberian Nanotechnology Laboratory, Braga (Portugal)

Scanning Tunneling Microscope (STM) makes it possible to fabricate and probe magnetic nanostructures with atomic resolution, going from individual atoms up to arrays of spin chains. These systems lie in the borderline between two opposite regimes, the quantum, reflected in the discrete nature of the spin excitations apparent in the inelastic electron tunneling spectroscopy (IETS), and classical, with finite magnetization. The displayed regime depends not only on their size [1,2], but also on the strength of their coupling to the environment.

Thus, the theoretical description of these magnetic adsorbates requires to deal with both, the quantum nature and the coupling to the environment. The first is accounted for by an effective spin Hamiltonian [1-4]. The energy and momentum transfer can be then described by an exchange coupling with the adsorbate spin. In weakly coupled systems, the dynamics of the adatoms can be study using a perturbative treatment of the exchange coupling together with a master equation for the reduced density matrix. This treatment correctly depicts the observed features in IETS while it allows identifying the decoherence and relaxation mechanisms [3]. It has further succeeded in explaining the magnetoresistive response when the adatoms are probed by a spin-polarized STM tip [3] or the observed energy shift when the exchange coupling is modulated along the substrate [4].

1. S. Loth, S. Baumann, C. P. Lutz et al., Sience 335, 196 (2012) 2. F. Delgado et al, in preparation 3. F. Delgado and J. Fernández-Rossier, Phys. Rev. B 82, 134414 (2010) 4. J. C. Oberg, M. R. Calvo, F. Delgado et al., Nature Nanotechnology 9, 64 (2014).

Magnetic Force Microscopy Imaging In Liquid

P. Ares1,2, M. Jaafar3, A. Gil1, J. Gómez-Herrero2, A. Asenjo3 1 Nanotec Electrónica S.L., Tres Cantos (Madrid), Spain 2 Dpto. Física de la Materia Condensada -

Universidad Autónoma de Madrid, Madrid, Spain3 Instituto de Ciencia de Materiales de Madrid - CSIC, 28049, Madrid, Spain

In this work, we present Magnetic Force Microscopy (MFM) images acquired in liquid environment. As is well known, MFM in liquid is a challenge as a consequence of the low quality factor (Q) of the cantilever resonance characteristic of liquid measurements. This low Q results in a significant loss of sensitivity in the MFM signal. Nevertheless, the capability of measuring magnetic nanostructures in liquid environment starts up new strategies in the characterization of nanoparticles for cancer treatment, or in vitro biological magnetic material of high interest in nanomedicine, as for instance viral cages with a magnetic cargo.

We use a Nanotec Electrónica AFM system controlled by WSxM software [1]. As a benchmark for this work we use a high density magnetic hard disk drive (Samsung HM320JI) with magnetic motif of ~60 nm. Commercial MFM probes (Nanosensor PPP-MFMR) are used. For the sake of comparison we first acquire MFM images in air ambient conditions in both Amplitude (AM-


AFM) and Drive Amplitude (DAM-AFM) Modulation modes [2, 3], obtaining similar results. For the images in liquid environment we use a specially designed acoustic driver cantilever holder [4] to minimize the resonance forest peak characteristic of acoustic drive in liquids. The lift distances used during the MFM signal recording are 15 nm in air and 6 nm in liquid.

Figures 1 a and b show two magnetic signal images acquired in air ambient conditions at two different oscillation amplitudes (10 and 5 nm), where a clear magnetic contrast between the different bits of the surface can be readily observed. Figures 1 c and d show the corresponding MFM images taken in liquid environment (images in air and liquid are acquired in different regions of the hard drive surface), where, despite the reduction in the signal-to-noise ratio (see inset profiles), the magnetic contrast can be easily seen as well, keeping a good lateral resolution.

The magnetic contrast observed in liquid environment in our work has been highly optimized [5]. In the presentation we discuss the origin of this optimization that will allow the study of a variety of magnetic materials in liquid.

I Horcas et al, Review of Scientific Instruments 78 (2007) p.013705 R García and R Pérez, Surface Science Reports 47 (2002) p.197-301 M Jaafar et al, Beilstein Joural of Nanotechnology 3 (2012) p.336-344 C Carrasco et al, Review of Scientific Instruments 79 (2008) p.126106 R Giles et al, Applied Physics Letters 63 (1993) p.617

State Of A Single Molecule By Local Gating On A Semiconductor Surface

Jesús Martínez-Blanco1, Christophe Nacci

1, Kyoshi Kanisawa

2, Steven Erwin

3, Stefan

Fölsch1

1 Paul-Drude-Institut für Festkörperelektronik. Berlin, Germany 2 NTT Basic Research Laboratories.

Atsugi, Japan 3 Center for Computational Materials Science, Naval Research Laboratory. Washington D.C., USA

InAs(111)A is a semiconductor surface that provides a unique playground in which the charge state of any adsorbed object, like an adatom or a molecule, can be probed directly by measuring the local surface band bending induced by the charged object. At the same time, the surface electrostatic potential can be tailored locally by indium adatoms, which can be manipulated at 5 K with the STM tip, and which remain positively charged on the surface due

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to their donor character. Taking advantage of these features, we study the charge state of single phthalocyanine molecules adsorbed on this surface. We engineer the electrostatic potential around the molecule by constructing different indium nanostructures nearby. In this way we are able to apply a gating potential to the surface-molecule-tip system. Tuning this gating potential appropriately, we observe a charge bistability at the location of the molecule for bias voltages around zero volts, transforming it into a single molecule charge switcher. We provide a full characterization of this system and discuss the possible mechanisms leading to its bistability.

Vector Mapping Of The Magnetic Moment Of Individual Atoms Using Spin Polarized STM

M. Moro1, M. Piantek

2, J. I. Pascual

3, M. R. Ibarra

1, D. Serrate

1

1 Instituto de Nanociencia de Aragón (INA) and Laboratory for Advanced Microscopy (LMA), University of Zaragoza, Spain 2 Instituto de Ciencias de Materiales de Aragón (ICMA), University of Zaragoza-CSIC,

Spain 3 Nanoscience Cooperative Research Center (CIC Nanogune)

Understanding and controlling the magnetic state of adatoms on a surface is of crucial importance in the development of spin based technology. Research in this field calls for a suitable technique able to observe and manipulate the spin of magnetic impurities. For that purpose we use spin polarized scanning tunneling microscopy (SP-STM), combining high magnetic lateral resolution and atom manipulation capability. In SP-STM, the magnetization easy axis of the tip determines the spin direction sensitivity for the sample system [1]. The tunneling magnetoresistance effect, upon which SP-STM relies, precludes sensing simultaneously two orthogonal spin directions of the sample with the same tip. In this work, we demonstrate that the easy axis of the SP-tip can be changed controllably from in-plane to out of plane and viceversa. This is achieved by transferring a single Co atom to a Fe coated W tip or dropping it by means of vertical manipulation methods. In the range of one monolayer on W(110), Mn orders magnetically as an antiferromagnetic spin spiral propagating along the [1-10] direction [2]. Such magnetic structure gives rise to a distinct spin resolved contrast that allows us to measure the evolution the SP-tip sensitivity direction. Besides, Co atoms placed at


designated positions over the spin-spiral display an apparent shape and height strongly dependent on their spin direction [3]. The changes observed in the tip magnetization direction upon picking/dropping a Co atom are further confirmed attending at the spin resolved contrast of the atoms remaining on the surface.

Our results show that a controlled rotation of 90° in the magnetization direction of a SPtip is possible, giving rise to a powerful tool for the characterization of novel magnetic materials in absence of magnetic field.

Kubetzka, A. et al. PRL 88, 57201 (2002) Bode, M. et al. Nature 447, 190-193 (2007) Serrate, D. et al. Nature Nanotechnology 5, 350-353 (2010)

On-Surface Synthesis Of BN/Graphene Hybrid Structures

Carlos Sanchez-Sanchez1, Matthias Müller

2, Holger F. Bettinger

2, Sebastian Brüller

3,

Klaus Müllen3, Leopold Talirz

1, Carlo Pignedoli

1, Pascal Ruffieux

1, Roman Fasel

1

1 Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600

Dübendorf, Switzerland 2 Institut für Organische Chemie, Universität Tübingen, Auf der Morgenstelle 18,

72076 Tübingen, Germany 3 Max Planck Institute for Polymer Research, 55128 Mainz, Germany

The absence of an electronic band gap is a major obstacle to the fabrication of efficient graphenebased switching devices. Different strategies, including top-down structuring and chemical modifications, have been proposed to transform graphene into a semiconductor [1]. However, most of these strategies lack accurate control on the resulting structures. Atomic level accuracy can be achieved by bottom-up strategies based on the surface-assisted colligation and transformation of suitably designed precursor monomers, which has proven to yield atomically precise surfacesupported nanoarchitectures. For instance, fullerenes and azafullerenes, nanodomes, and nanographenes have been synthesized via Surface-Assisted Cyclodehydrogenation (SACDH). Furthermore, the combination of SACDH with surface-catalyzed Ullmann coupling has been used for the synthesis of atomically precise graphene nanoribbons (GNR) and porous graphene, where electron confinement yields the appearance of a band-gap [2,3].

Here we will show how the combination of SACDH and Ullmann coupling

on metallic surfaces under ultra-high vacuum conditions allows for the formation of 2D BN/graphene hybrid networks, which are unavailable via traditional solution-based chemistry. We find that high-resolution scanning tunneling microscopy (STM) images together with density functional theory calculations allow the identification of the position and orientation of the borazine rings. Our proof-of-concept study opens the door towards the design and synthesis of atomically precise heterostructures by tailoring of precursor monomers.

[1] D. Jariwala, A. Srivastava and P. M. Ajayan. http://arxiv.org/ftp/arxiv/papers/1108/1108.4141.pdf [2] J. Mendez, M. F. Lopez, J.A. Martin-Gago, Chem. Soc. Rev., 2011, 40, 4578-4590. [3] J. Björk, and F. Hanke, Chem. Eur. J. 2014, 20, 928 – 934.

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Charge-transfer Induced Isomerization Of DCNQI On Cu(100)

C. Urban1, Y. Wang1,2, J. Rodríguez-Fernández1, M. A. Herranz3, M. Alcamí1, N. Martín2,3

,

F. Martín1,2

, J. M. Gallego2,4

, R. Otero1,2

, R. Miranda1,2

1 Universidad Autónoma de Madrid. Madrid. 2 IMDEA-Nanociencia. Madrid. 3 Universidad Complutense

de Madrid. Madrid. 4 ICMM-CSIC. Madrid.

Cis-trans isomerization reactions have been recently proposed as models for the action of molecular-scale switches. Molecules like azobenzene derivatives have thus been deposited on solid surfaces and the isomerization reaction has been induced by external influences such as the tunneling current of an STM or light irradiation. Although the catalytic action of the surface on such reactions is amply acknowledged in previous works, understanding the exact mechanism of such reactions still requires further studies. Moreover, the effect of temperature on such reaction has not been studied at any extent. Here we show STM and DFT results on the thermally-controlled isomerization of the DCNQI molecules adsorbed on Cu(100). Depending on the substrate temperature two different molecular arrangements are observed, along with two different appearances of the molecules in STM images. Comparison with DFT calculations shows that whereas the low-temperature phase is consistent with a trans-geometry of the cyano groups with respect to the molecular axis, at higher temperatures such arrangement is formed exclusively with cis-isomers. The transition temperature, -30°C, is too low for the molecule in the neutral form to undergo such cis-trans isomerization, and thus a catalytic effect of the substrate must exist. Based on our experimental results and theoretical calculations we attribute such catalytic effect to charge-transfer from the metal to the molecule along with a strong bonding between the cyano groups and the copper atoms of the substrate. Charge-transfer lowers the cis-trans isomerization barrier in two synergistic ways. First it aromatizes the quinoid ring into a benzene ring, enabling a freer rotation of the cyano groups with respect to the molecular axis. Second, such easier rotation leads to an enhanced interaction of the cyano groups with the copper atoms of the substrate that brings the two isomeric forms closer to each other than in the gas phase conformation


Theoretical STM Characterization Of On-surface Reactions Of Heteroaromatics

Jose Ignacio Martinez1, Anna Lisa Pinardi

1, Gonzalo Otero-Irurueta

1, Maria Francisca

Lopez1, Javier Mendez

1, Jose Angel Martin-Gago

1

1 Dept. de Superficies y Recubrimientos (ICMM / CSIC), ES-28049 Madrid, Spain

Understanding the interaction between organic molecules and surfaces is of paramount importance in diverse fields such as organic electronics, molecular electronics, catalysis, and surface photochemistry, among others. In particular, the bottom-up approach aims at forming tailored nanoarchitectures by manipulating organic molecules at atomic level and it is one of the most effective strategies used in nanotechnology. Catalytic surfaces are often used to prompt a particular reaction as they are very successful in modifying a particular molecule in selected ways. For example, transition metal surfaces are very efficient catalysts of dehydrogenation reactions in Polycyclic Aromatic Hydrocarbon (PAH), usually upon thermal activation. They can act in different ways, depending on the strength of the interaction between the surface and the adsorbate [1]. When a PAH is deposited on a reactive surface, such as Pt(111), the molecule does not diffuse, so the as-deposited molecule sticks where it lands. When this system is annealed, the molecule dehydrogenates which results in an intramolecular transformation, as no intermolecular interaction is allowed as the molecules do not “see” each other. An adequate combination of first-principles calculations, including vdW interactions, with an accurate theoretical STM imaging approach based on the Keldish-Green formalism [2], permits the monitoring and full characterization of the different intermediate steps along the whole thermal-induced dehydrogenation process [1]. Following this line, our research group has recently shown the catalytic properties of the TiO2 (110)-(1×1) surface towards dehydrogenation of large organic molecules [3]. In this case, we have deposited C60H30 molecules on this surface and we have proven that high temperature annealing leads to partial cyclodehydrogenation, which allows the use of the activated PAHs as building blocks for larger nanostructures. In this way, the formation of fullerene-like nanodomes on this dielectric surface was observed by STM. The different stages of this on-surface chemistry were followed by different experimental techniques (STM, XPS and NEXAFS), and fully characterized by the mentioned theoretical framework. For this particular interface, theory shed some light on the origin of the two different sets of molecules observed in the UHV-STM images, one vanishing for certain values of the external tunnelling bias, and the other set of molecules observed at all range of bias, which is directly related to the dehydrogenation stage of the molecules [3].

A. L. Pinardi, J. I. Martínez, J. A. Martín-Gago et al., ACS Nano 7(4), (2013) 3676; Chem. Comm. 50, (2014) 1555.

J. P. Lewis et al., Phys. Stat. Sol. B 248, (2011) 1989; J. M. Blanco et al., Phys. Rev. B 70, (2004) 085405. C. Sánchez-Sánchez, J. I. Martínez, J. A. Martín-Gago et al., Nanoscale 5, (2013) 11058.

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Customizing Metallocene layers on Cu(111)

Ormaza Maider1, Bachellier Nicolas

1, Bocquet Marie-Laure

2, Lorente Nicolas

3, Limot

Laurent1

1Institut de Physique et Chimie des Matériaux de Strasbourg, CNRS-UdS, 67034 Strasbourg, France

2Université de Lyon, Laboratoire de Chimie, Ecole Normale Supérieure de Lyon, CNRS, France 3Centro de Investigación en Nanociencia y Nanotecnología (CSIC-ICN), Bellaterra E-08193, Spain

Metallocene double-decker molecules have received considerable interest over the past two decades due to their application as catalysts and organometallic polymers with magnetic properties. More recently, it has been predicted that these molecules present unique spin transport properties, behaving in fact as halfmetallic ferromagnets [1]. Despite this promising prediction, electron transport across metallocene molecules is yet to be explored.

Here we use Scanning Tunneling Microscopy (STM) to characterize the adsorption and electronic properties of ferrocene (FeCp2, Cp=C5H5) and cobaltocene (CoCp2) on metallic surfaces. In particular, we show, with the support of DFT, that these molecules self-assemble forming ordered molecular monolayers (fig. 1) and that the nature of the central atoms plays an important role determining the molecular self-assembly. Most importantly, we demonstrate that the deposition of adatoms onto the molecular layer leads to the formation of novel triple-decker molecules which carry a Kondo effect.

Fig. 1: FeCp2 network with cobalt atoms (-1V, 0.5 nA)

[1]. L. Wang et al., Nano Lett. 8, 3640 (2008)

Electron Scattering Of Rashba-split States In The BiAg2 Surface Alloy

S. Schirone7, R. Piquerel

7, G. Bihlmayer

6, E. E. Krasovskii

3,4,5, P. Gambardella

1,2,7, A.

Mugarza7

1 ICREA - Institucio Catalana de Recerca i Estudis Avancats, E-08193 Barcelona, Spain 2 Department of

Materials, ETH Zurich, Hönggerbergring 64, CH-8093 Zurich, Switzerland 3 Dpto. de Física de Materiales

UPV/EHU, Facultad de Quimica, Paseo Manuel de Lardizabal 3, E-20018, San Sebastián, Spain 4 Donostia

International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, E-20018 San Sebastián, Spain 5

IKERBASQUE, Basque Foundation for Science, E-48011 Bilbao, Spain 6 Institute for Advanced Simulation


and Peter Grünberg Institut 1, Forschungszentrum Jülich, D52425 Jülich, Germany 7 ICN2 - Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, E-08193 Bellaterra (Barcelona), Spain

Spin-orbit interaction (SOI) in metallic surfaces can lead, via the Rashba effect, to a splitting of the spin degeneracy and the emergence of particular spin textures that are related to the entanglement between spin and orbital momentum. Here we use the BiAg2 surface alloy, which is characterized by the strongest to date Rashba effect [1,2], to study the effect of SOI on scattering. The alloy is formed on the Ag(111) surface after the deposition of 1/3 monolayer of Bismuth. The scattering has been studied using Scanning Tunnelling Microscopy and Spectroscopy (STM/STS). In this way we have studied electron confinement by measuring the interference patterns formed by surface electrons scattered from monoatomic steps. We find that scattering is determined by i) an unconventional orbital/spin texture of the surface bands, which give rise to transitions with combined orbital and spin flips, and ii) by its chemical composition, which defines a heterogeneous electron localization and potential landscape. The negligible leakage we observe across some step structures indicate a strong confinement effect, comparable to that observed in metals with marginal SOI such as Ag

(111) [3]. The results describe a scenario that is far more complex than the conventional Rashba-type two dimensional free-electron gas.

Figure 1: (a) Topographic image of a zone of the sample with different type of monoatomical step,acquired with I_t=0.59 nA and V_bias =0.2 V . Image size: 406×406 Å^2. (b) dI⁄dV-map acquired acquired at V_bias =+0.4 V . Note that the intensity of the standing wave scattered from the two kind of steps is different. (c) Topographic image performed with I_t= 0.59 nA . V_bias= 28 mVImage size: 164×110 Å^2. The surface lattice structure is resolved in the image, and the different termination of each step type can be distinguished. (d) Schematics of the lattice of the surface alloy. Solid lines indicate the direction of each step type.

C. Ast, J. Henk, A. Ernst, L. Moreschini, M. C. Falub, D. Pacile, P. Bruno, K. Kern, and M. Grioni, Phys. Rev. Lett.

98, 186807 (2007). G. Bihlmayer, S. Blügel, and E. V Chulkov, Phys. Rev. B 75, 195414 (2007). J. E. Ortega, J. Lobo-Checa, G. Peschel, S. Schirone, Z. M. Abd-El-Fattah, M. Matena, F. Schiller, P. Borghetti, P.

Gambardella, and A. Mugarza, Phys. Rev. B 87, 115425 (2013).

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Graphene tunable electronic tunneling transparency: A unique tool to measure the local coupling

H. González-Herrero1, A.J. Martínez-Galera2, M.M. Ugeda1, F. Craes2, D. Fernández-Torre3, P. Pou3, R. Pérez3, J.M. Gómez-Rodríguez1 and I. Brihuega 1.

1 Dept. Física de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 , Spain 2II. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany 3 Dept. de

Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid,,Spain

Graphene grown on metals has proven to be an excellent approach to obtain high quality graphene films [1,2]. However, special care has to be taken in order to understand the interaction of graphene with the substrate, since it can strongly modify its properties even in apparently weakly coupled systems [3]

Here, we have grown one monolayer graphene on Cu (111) by using a new technique consisting in the thermal decomposition of low energy ethylene ions irradiated on a hot copper surface [4]. By means of low temperature STM/STS experiments, complemented by density functional theory calculations, we have obtained information about the structural and electronic properties of our graphene samples with atomic precision and high energy resolution. Our work shows that depending on the STM tip apex and the tunnel parameters we can get access to either the graphene layer, the copper surface underneath or even both at the same time, see Figure 1. This fact provides a unique tool to investigate the local coupling between the graphene layer and the metal underneath. Moreover, this approach can also be applied to investigate the interaction of point defects in the graphene layer with the underlying substrate [5].

Figure 1: Same 60x60 nm2 terrace measured with different tunneling conditions. Left side: the moiré pattern of the graphene layer is observed. Right side: the standing-waves patterns associated with the Cu(111) surface state below the graphene layer are observed. Both images are measured at 6K

[1]. J. Wintterlin and M. L. Bocquet, Surf. Sci. 603, 1841(2009). [2]. X. S. Li et al., Science, 324, 1312 (2009). [3]. I. Brihuega, P. Mallet, H. González-Herrero et al. Phys. Rev. Lett. 109, 196802 (2012). [4]. A.J. Martínez-Galera, I. Brihuega and J. M. Gómez-Rodríguez, Nano Letters 11, 3576 (2011). [5]. M. M. Ugeda, D. Fernández-Torre, I. Brihuega et al., Phys. Rev. Lett. 107, 116803 (2011).

Tunnelingto Cu(111)Tunneling

to graphene


Graphene Etching On SiC Grains As A Path To Interstellar Polycyclic Aromatic Hydrocarbons Formation

P. Merino1, M. Švec

2, J.I. Martinez

3, P. Jelinek

2, P. Lacovig

4, M. Dalmiglio

4, S. Lizzit

4, P.

Soukiassian5, J. Cernicharo

1, J.A. Martin-Gago

1,3

1 Centro de Astrobiología INTA-CSIC, Carretera de Ajalvir, km.4, ES-28850 Madrid, Spain 2 Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, CZ-16200 Prague, Czech Republic 3 Instituto Ciencia de Materiales de Madrid-CSIC, c/. Sor Juana Inés de la Cruz, 3, ES-28049 Madrid, Spain

4 Elettra-Sincrotrone Trieste S.C.p.A., Area Science Park, S.S. 14, Km 163.5, I-34149 Trieste, Italy 5 Commissariat à l’Energie Atomique et aux Energies Alternatives, SIMA, DSM-IRAMIS-SPEC, Bât. 462,

91191 Gif sur Yvette, France

Polycyclic aromatic hydrocarbons as well as other organic molecules appear among the most a bundant observed species in interstellar space and are key molecules to understanding the prebiotic roots of life. However, their existence and abundance in space remain a puzzle. Here present a new top-down route to form polycyclic aromatic hydrocarbons in large quantities in space. We show that aromatic species can be efficiently formed on the graphitized surface of the abundant silicon carbide stardust on exposure to atomic hydrogen under pressure and temperature conditions analogous to those of the interstellar medium. To this aim, we mimic the circumstellar environment using ultra-high vacuum chambers and investigate the SiC surface by in situ advanced characterization techniques combined with first-principles molecular dynamics calculations. These results suggest that top-down routes are crucial to astrochemistry to explain the abundance of organic species and to uncover the origin of unidentified infrared emission features from advanced observations.

Figure: False color STM image of a hole in the middle of a graphene terrace. These holes are observed after H treatment at high temperatures and evidence etching through edges and defects. 70x70nm2,-1.1V.

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Observation Of Giant Bandgap Renormalization And Excitonic Effects In A Monolayer Transition Metal Dichalcogenide Semiconductor

Miguel M. Ugeda1, Aaron J. Bradley

1, Su-Fei Shi

1, Felipe H. da Jornada

1,2, Yi Zhang

3,4,

Diana Y. Qiu1,2

, Sung-Kwan Mo3, Zahid Hussain3, Zhi-Xun Shen4,5, Feng Wang1,2, Steven G. Louie1,2, Michael F. Crommie1,2

1 Department of Physics, University of California at Berkeley, Berkeley, CA, USA. 2 Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA. 3 Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA. 4 Stanford Institute for Materials and Energy Sciences,

SLAC National Accelerator Laboratory, Menlo Park, CA, USA. 5 Geballe Laboratory for Advanced Materials, Departments of Physics and Applied Physics, Stanford University, Stanford, CA, USA.

Atomically-thin transition metal dichalcogenide (TMD) semiconductors have generated great interest recently due to their remarkable physical properties. For example, reduced screening in 2D has been predicted to result in dramatically enhanced Coulomb interactions that should cause giant bandgap renormalization and excitonic effects in single-layer TMD semiconductors. [1, 2]. Here we present a direct experimental observation of extraordinarily high exciton binding energy and band structure renormalization in a single-layer of semiconducting TMD [3]. We determined the binding energy of correlated electron-hole excitations in monolayer MoSe2 grown on bilayer graphene (BLG) using a combination of high-resolution scanning tunneling spectroscopy (STS) and photoluminescence spectroscopy. We have measured both the quasiparticle electronic bandgap and the optical transition energy of monolayer MoSe2/BLG, thus enabling us to obtain an exciton binding energy of 0.55 eV for this system, a value that is orders of magnitude larger than what is seen in conventional 3D semiconductors. We have corroborated these experimental findings through ab initio GW and Bethe-Salpeter equation calculations which show that the large exciton energy arises from enhanced Coulomb interactions that lead to a dramatic blue-shifting of the quasiparticle bandgap. In addition, we explored the low-energy electronic structure of single- and few-layer MoSe2. Our results reveal that the electronic properties of these materials are highly dependent on the number of layers (4). These results are of fundamental importance for the design and evaluation of room-temperature electronic and optoelectronic nanodevices involving single-layer semiconducting TMDs. This includes all optoelectronic applications, such as solar cells and new valleytronic schemes, either in stand-alone devices or within integrated heterostructures. More fundamentally, the excitonic nature of the optical response for single-layer MoSe2 highlights the importance of many-body effects in atomically-thin 2D layers.

H. P. Komsa, A. V. Krasheninnikov, Physical Review B. 86, 241201 (2012). D. Y. Qiu, F. H. da Jornada, S. G. Louie, Physical Review Letters. 111, 216805 (2013). M. M. Ugeda, A. J. Bradley, et al., Submitted. A. J. Bradley, M. M. Ugeda, et al., Manuscript in preparation.

Electrostatic Manipulation Of Graphene On Graphite

C. Rubio-Verdú1, J. Martínez

1, M.J. Caturla

1, G. Sáenz-Arce

1, D. C. Milán

1, C. Untiedt

1

1 Department of Applied Physics, University of Alicante


Here we report the use of a Scanning Tunneling Microscope (STM) under ambient and vacuum conditions to study the controlled exfoliation of the last layer of a graphite surface when an electrostatic force is applied from a STM tip. In this work we have focused on the study of two parameters: the applied voltage needed to compensate the graphite interlayer attractive force and the one needed to break atomic bonds to produce folded structures.

Additionally, we have studied the influence of edge structure in the breaking geometry. Independently of the edge orientation the graphite layer is found to tear through the zig-zag direction and the lifled layer shows a zig-zag folding direction.

Molecular Dinamics simulations have been performed showing a strong correlation with the experimental results.

AFM Technologies in personolized medical diagnostics

Christoph Gerber

Swiss Nanoscience Institute, Institute of Physics, University of Basel, Switzerland

Recently Atomic Force Microscopy (AFM) technologies have come of age in various biological applications. Moreover these developments has started to enter the clinic .From this nanotoolkit we use a micro-fabricated silicon cantilevers array platform as a novel biochemical highly sensitive sensor that offers a label-free approach for point of care fast diagnostics where ligand-receptor binding interactions occurring on the sensor generate nanomechanical signals like bending or a change in mass which is optically detected in-situ. It enables the detection of multiple unlabelled biomolecules simultaneously down to picomolar concentrations within minutes in differential measurements including reference cantilevers on an array of eight sensors. The sequence-specific detection of unlabelled DNA in specific gene fragments within a complete genome is shown. In particular the expression of the inducible gene interferon- a within total RNA fragments and unspecific back ground . This gives rise that the method allows monitoring gene regulation , an intrinsic step in shining light on disease progression on a genetic level. Moreover malignant melanoma, the deadliest form of skin cancer can be detected with this technology on a single point mutation without amplification and labeling in the background of the total RNA

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Looking back 30 years at Baro’s Laboratorio de Nuevas Microscopías: the recollections of a mid-western American

Ron Reifenberger

Purdue University, Department of Physics, West Lafayette IN USA

I will provide a retrospective look back at Prof. A.M. Baro’s role in promoting scanning probe research in mid-western America. Spanning the unbelievable days just after the STM was invented to the present, I will hi-light joint research between Baro’s lab at UAM and the scanning probe research conducted at Purdue University to illustrate the fruits of a 30 year, life-long international collaboration. In addition to a recitation of various scientific achievements, the talk includes photos and recollections of ‘la forma en que fue’ which will support the hypothesis that we should judge our life by the memories, not by the years.

Scanning the trends of Atomic Force Microscopy

Arvind Raman

Robert V. Adams Professor of Mechanical Engineering, Purdue University, Department of Physics, West Lafayette IN USA

The American baseball great Yogi Berra once reputedly said “The future ain’t what it used to be” referring to the pitfalls of using trends to predict the future. So too can be said of the field of AFM. The last two decades have seen an astonishing number of technological innovations, some that have staying power and others that are no longer popular. And yet the AFM has advanced much in the past two decades. In this talk we will discuss some of these past and present trends with a view to learning from these examples. We will discuss competing microscopies and broad tendencies in the AFM field today that may suggest near future directions in the field at very broad level.

Tunneling Microscopy: Retrospectives and perspectives

Ignacio Pascual

CIC Nanogune, Donosti-San Sebastián, Spain

Arturo Baró was witness and actor of the born and development of probe microscopies during the last three decades. During this time, tunneling microscopes spanned in areas of chemistry and physics with such strong impact that changed in many respects our approach do science. This “new science”, the “Science of the Local Information in the Real Space”, manipulates mater at the atomic scale, measures electrons in reciprocal space, and currently advances to cover frequency and time domains. A retrospective of its development entails an overview of classical problems in condensed matter and physical-chemistry, to which local probes contributed to advance. In this talk, I will give a very personal retrospective of Tunneling Microscopy and Spectroscopy beyond imaging, as well as trends and perspectives for the coming years.

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Thrusday, August 28, 2014, San Sebastián, Spain 29

Realising quantitative dynamic atomic force microscopy to probe transactions of DNA at the single molecule level

Neil H Thomson1,2 1 Department of Oral Biology, School of Dentistry 2 Molecular and Nanoscale Physics Group, School of

Physics and Astronomy, University of Leeds, LS2 9JT, United Kingdom.

The dynamic modes of atomic force microscopy (dAFM), where the force sensing cantilever is oscillated at or close to resonance, have been essential for atomic force microscopy to reliably image and measure soft biological samples, from single molecules to cells. Extracting quantitative information has been hampered by a number of problems, including understanding the dynamics of the oscillating cantilever in the non-linear tip-sample potential and the response of the cantilever from the integration of forces of different origin (sign and length scale) by the AFM tip.

The first part will summarise a number of key advances our group has made towards making AFM measurements quantitative. It will demonstrate that loss of height at the nanoscale is a consequence of the intrinsic convolution between the force fields of the tip and sample [1]. A new in situ tip sizing technique was developed based on the bi-stable behaviour of the oscillating cantilever above the sample [2]. We have also shown that for DNA on hydrophilic surfaces such as mica, even in ambient conditions, there is sufficient water present to retain structural hydration of biomolecules [3]. Building on these three outcomes, we have been able to measure the hydrophilicity of individual DNA molecules, which indicates that DNA may be more hydrophobic than previously anticipated [4]. Furthermore, we have implemented a new imaging mode that maximises resolution and can resolve the right-handed DNA double helix in ambient [5].

The second part will concentrate on the use of amplitude modulation (AM AFM) imaging applied to DNA-protein complexes in ambient conditions. We are studying DNA transcription and investigating dual RNA polymerase transactions on single DNA templates in the context of the twin supercoiling domain paradigm [6]. The outcomes have implications for compressed genetic structures found in vivo and are giving foundation to understanding the “rules of the road” for these molecular motors that mediate gene expression.

Santos S., Barcons V., Christenson H.K., Font J. and Thomson N.H. (2011) PLoS ONE 6 (8): e23821. Santos S., Guang L., Souier T., Gadelrab K., Chiesa M. and Thomson N.H. (2012) Rev. Sci. Instrum. 83, 043707. Billingsley D.J., Kirkham J., Bonass W.A, and Thomson N.H. (2010) Phys. Chem. Chem. Phys. 12 (44), 14727 -

14734 Santos S., Stefancich M., Hernandez H., Chiesa M. and Thomson N.H. (2012) J. Phys. Chem. C 116 (4) 2807-

2818. Santos S., Barcons V., Christenson H.K., Billingsley D.J., Bonass W.A, Font J. and Thomson N.H. (2013) Applied

Physics Letters 103, 063702. Billingsley D.J., Bonass W.A, Crampton N., Kirkham J. and Thomson N.H. (2012) Physical Biology 9, 021001.


Imaging Of Biosystems By Dynamic Atomic Force Microscopy

Magali Phaner-Goutorbe 1 Université de Lyon, Institut des Nanotechnologies de Lyon (INL, UMR CNRS 5270), site Ecole Centrale

de Lyon, 36 avenue Guy de Collongue, 69134 Ecully, France E-mail: [email protected]

Using amplitude-mode AFM (AM-AFM), valuable information has been obtained during these recent years through the study of amplitude and phase shift dependence on tip-sample separation, leading to a comprehensive understanding of the interaction processes. Two imaging regimes, attractive and repulsive, have been identified and a relationship between phase and dissipative energy was established, providing information on observed material properties. Most of the previous studies have concerned model systems: either hard or soft materials [1-3].

In the case of biosystems, the sample is composed of biological macromolecules or thin bio/organic layers supported on mineral substrates. Then, this creates a mixed system of soft structures on a hard substrate. In this work, we propose to discuss about the dynamics of dissipation processes during scanning based on a real biosensor a DNA array, and demonstrated that information about the tip-surface interaction regime can be obtained [4]. The best experimental conditions to obtain specific information were determined: we got reliable conditions to minimize noise during topographic imaging and an understanding of the processes of energy dissipation involved in the DNA breaking for DNA arrays. By calculating the energy dissipated as a function of the amplitude of oscillation, we have demonstrated a transition from an energy dissipation process governed by localized viscoelastic interactions (due to the soft layer) to a process governed by extended irreversible deformations (due to the hard substrate). Examples of other biosystems were also presented [5, 6].

R. García, R. Pérez, Surf. Sci. Rep. 47, 197, (2002). N. F. Martínez, W. Kamiński, C. J. Gómez, C. Albonetti, F. Biscarini, R. Pérez, R. García, Nanotechnology 20,

434021, (2009). R. Garcia, C. J. Gomez, N.F. Martinez, S.Patil, C.Dietz, R. Magerle, Phys. Rev. Lett. 97, 016103, (2006). M. Phaner-Goutorbe, M. Iazykov,R. Villey, D. Sicard, Y. Robach, Materials Science and Engineering C 33, 2311-

2316, (2013) D. Sicard, Y. Chevolot, E. Souteyrand, S. Vidal, M. Phaner-Goutorbe, J. Mol. Recognit., 26, 694, (2013) D. Sicard, S. Cecioni, M. Iazykov, Y. Chevolot, S. Mathews, J-P. Praly, E. Souteyrand, A. Imberty, S.Vidal, M.

Phaner-Goutorbe, Chem. Commun., 47 (33), 9483 – 9485, (2011)

Fast Nanomechanical Spectroscopy of Soft Matter

E. T. Herruzo, A.P. Perrino , R. Garcia

Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), Madrid

A method that combines high spatial resolution, quantitative and non-destructive mapping of surfaces and interfaces is a long standing goal in nanoscale microscopy. The method would facilitate the development of hybrid devices and materials made up of nanostructures of different properties.

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Bimodal atomic force microscopy is a multifrequency dynamic force method based on the simultaneous excitation of two eigenmodes of the cantilever [1,2]. We have developed a multifrequency force microscopy method that enables the simultaneous mapping of the nanomechanical spectra of soft matter surfaces with nanoscale spatial resolution [3,4]. The properties include the Young modulus and the viscous or damping coefficients. In addition, it provides the peak force and the indentation. The method has been tested on different polymers and proteins in air with near four orders of the magnitude variations in the elastic modulus, from 1 MPa to 3 GPa. The method does not limit the data acquisition speed or the spatial resolution of the force microscope. It is non-invasive and minimizes the influence of the tip radius on the measurements. The use of several information channels (first and second mode) results in the calculation of Young modulus and viscosity coefficients which do not depend on the applied force. The results coincide with the results obtained by other well-established methods (static AFM, force inversion methods).

Figure: (a) Indentation map in a block copolymer (PS-b-PMMA) thin film (scale bar, 100 nm). (b) Map of the elastic modulus of PS-b-PMMA (scale bar, 100 nm). (c) Cross-section along the dashed line shown in a. (d) Histogram of the elastic modulus obtained from b.

[1]. R. Garcia and E.T. Herruzo.Nat. Nanotechnol. 7, 217-226 (2012). [2]. D. Martinez-Martin, E.T. Herruzo, C. Dietz, J. Gomez-Herrero and R. Garcia. Phys. Rev. Lett. 106, 198101

(2011) [3]. E. T. Herruzo and R. Garcia. Beilstein J. Nanotechnol. 3, 198–206 (2012) [4]. E. T. Herruzo, A.P. Perrino and R.Garcia. Nat. Comm. 3, 3126 (2014)

Mechanical uncoating of a virus genome: an AFM-TIRF combined experiment

A. Ortega-Esteban1*, K. Bodensiek2*, G. Condezo3, M. Suomalainen4, U. Greber4, C. San Martín3, P. J. De Pablo1, I. A. T. Schaap2

1Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid, Spain 2Fakultät für Physik, III. Physikalisches Institut, Georg August Universität, Göttingen, Germany


3Department of Macromolecular Structures, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain 4Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland

* These authors contributed equally to this work

In the infection pathway of human adenovirus, the icosahedral viral cage suffers a stepwise disruption starting by losing the vertices (pentons). A partially disrupted particle docks to nuclear pores releasing the genome inside the cell nucleus. The details of DNA diffusion out of the virus during this process remain elusive. Previous studies with Atomic Force Microscopy (AFM) in liquids demonstrated that mechanical disruption of viral cages in a controlled way recapitulates the stepwise uncoating process occurring in the cell. However DNA diffusion occurs in a 3D fashion, impairing the study of this process by 2D techniques such as AFM, which requires the immobilization of biomolecules on surfaces. Therefore, we have designed and carried out experiments combining Total Internal Reflection Fluorescence Microscopy (TIRF) and AFM, where both techniques are used in a complementary way to characterize DNA release from human adenovirus cages. In our studies, we induce the mechanical uncoating of individual adenovirus particles with AFM and, simultaneously, monitor DNA diffusion with TIRF. Our preliminary results establish a direct relationship between the compaction of viral genome and its diffusion outside the viral shell as revealed by TIRF data.

Mechanical Properties Of Antibodies As Measured By AFM: An Atomistic Molecular Dynamics Study

J.G. Vilhena1,2

, Pedro A. Serena1, Ruben Perez

2

1 Instituto de Ciencia de Materiales de Madrid, CSIC, Madrid , Spain 2 Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, Madrid, Spain

Antibodies are key elements of the immune system. A better understanding of their nanomechanical properties could allow exploiting all of their targeting properties. Recent advances on molecular-dynamics (MD) simulations allow studying such large systems with an atomistic detail. Furthermore, the newly developed high-resolution multi-frequency atomic-force-microscopy (MF-AFM) provides now information about the nanomechanics of proteins[1]. Here we have combined both techniques to measure the flexibility map of the IgG antibody (150kDa), the second most abundant plasma protein that provides the majority of antibody-based immune response. AFM experiments are modeled performing many (>60) steered molecular dynamics sampled over long equilibrations (>100ns), thus obtaining large statistics and small error on the indentation forces. The tip and the supporting substrate for the IgG adsorption are modeled as a capped carbon nanotube and a three layers slab of graphite, respectively. Our results[2] address the ultimate spatial resolution and force sensitivity of MF-AFM on biological samples, as well as the role played by water molecules on the indentation process.

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R. Garcia et al; PRL 106, 198101 (2011) Mechanical properties of antibodies: an atomistic MD and MF-AFM study; in preparation.

Structural Analysis Of Individual Protein Complexes By Infrared Scattering At An AFM Tip

Iban Amenabar1, Simon Poly

1, Wiwat Nuansing

1, Elmar H. Hubrich

3, Alexander A.

Govyadinov1, Florian Huth

1,2, Roman Krutokhvostov

1, Lianbing Zhang

1, Mato Knez

1,4,

Joachim Heberle3, Alexander Bittner

1,4, Rainer Hillenbrand

1,4

1 CIC nanoGUNE Consolider, 20018 Donostia - San Sebastián, Spain 2 Neaspec GmbH, 82152 Martinsried,

Germany 3 Experimental Molecular Biophysics, Department of Physics, Freie Universität Berlin, D-14195

Berlin, Germany 4 IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain

We introduce the mapping of protein structure with 30 nm lateral resolution and sensitivity to individual protein complexes by infrared scattering-type scanning near-field optical microscopy (IR s-SNOM) and Fourier transform infrared nanospectroscopy (nano-FTIR). s-SNOM and nano-FTIR are based on r ecording the infrared light scattered by a metallized atomic force microscope tip probing the sample surface. We present and discuss local broadband spectra of individual viruses, ferritin complexes, purple membranes and insulin aggregates, which can be interpreted in terms of their alpha-helical and/or betasheet structure [1]. Applying nano-FTIR for studying insulin fibrils - a model system widely used in neurodegenerative disease research - we find clear evidence that 3-nm-thin amyloid-like fibrils contain a large amount of alpha-helical structure. Nano-FTIR spectra of one ferritin complex demonstrate extraordinary sensitivity to ultra-small amounts of material, about 1 attogram of protein, respectively 5000 C=O bonds. By further sharpening the tips and optimizing their antenna performance, we envision single protein spectroscopy in the future, paving the way to a new era in infrared bio-spectroscopy. We foresee manifold applications, such as studies of conformational changes in amyloid structures on the molecular level, the mapping of nanoscale protein modifications in biomedical tissue or the label-free mapping of membrane proteins.


Amenabar I, Poly S, Nuansing W, Hubrich E, Govyadinov A, Huth F, Krutokhvostov R, Zhang L, Knez M, Heberle

J, Bittner A, Hillenbrand R. Structural analysis and mapping of individual protein complexes by infrared nanospectroscopy. Nature Communications 2013,4:2890

Scattering Properties Of Graphene Nanostructures On Ni(111)

A. Garcia-Lekue1,2

, T. Balashov3, M. Ollé

3, G. Ceballos

3, A. Arnau

1,4,5, P. Gambardella

3,6,7,

D. Sánchez-Portal1,4

, A. Mugarza3

1 Donostia International Physics Center (DIPC). Donostia-San Sebastian. 2 IKERBASQUE, Basque

Foundation for Science, Bilbao. 3 Catalan Institute of Nanoscience and Nanotecnology (ICN2), Bellaterra. 4 Centro de Física de Materiales CFM, Centro Mixto CSIC-UPV, Donostia-San Sebastian. 5 Dpto. de Física

de Materiales UPV/EHU, Facultad de Química, Donostia-San Sebastian. 6 Institució Catalana de Recerca i

Estudis Avançats (ICREA), Barcelona. 7 Department of Materials, ETH Zurich, Zurich.

The graphene-metal interaction can be exploited to engineer hybrid structures with novel electronic and magnetic properties. The graphene-Ni interface is an interesting case where the interaction with the ferromagnetic substrate opens hybridization gaps and induces magnetic moments.[1,2] We investigate the electronic properties of graphene nanoislands grown on Ni(111), [3] using local tunneling spectroscopy measurements combined with spin-polarized ab initio calculations.[4] We show that the electron scattering at the graphene edges is found to be spin- and edge-dependent. This behavior is attributed to the strong distortion of the electronic structure at the interface, which opens a gap and spin-polarizes the Dirac bands of graphene. We also demonstrate that edge scattering is strongly structure dependent, with asymmetries in the reflection amplitude of up to 30% for reconstructed and unreconstructed zig-zag edges.[5] These results suggest a lateral 2D spin filtering for graphene layers, similar to that occurring

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Figure: (a) Topographic (top) and constant current dI/dV map (bottom) showing the interference pattern of the surface state scattered from graphene islands. (c) Calculated planar average density of the majority and minority surface states of Ni(111) at the Г point.

V. M. Karpan et al. Phys. Rev. Lett. 99, 176602 (2007) M. Weser et al., Appl. Phys. Lett. 96, 012504 (2010) M. Olle et al. Nano Lett. 12, 4431 (2012). A. Garcia-Lekue et al., Phys. Rev. Lett. 112, 066802 (2014) M. Olle et al., to be submitted.

Multidomain graphene on Rh(111): STM study of unusual moiré patterns

A. Martín-Recio1, A. J. Martínez-Galera1,2, J. M. Gómez-Ródriguez1

1 Depto. de Física de la Materia Condensada, Universidad Autónoma de Madrid, Spain; 2 Physikalisches Institut, Universität zu Köln, Zulpicher Str. 77, Köln, Germany

Through all the different graphene growth techniques developed during the last years, the chemical vapor deposition (CVD) on transition metals has demonstrated to be one of the best ones producing high quality, large scale graphene films. For this reason, the physics of graphene-metal interactions has attracted the attention of worldwide research[1]. When the carbon layer is grown on low reactive metals such as Pt(111)[2], Cu(111) or Au(111)[3], the low coupling between them leads to several rotational domains of the graphene layer giving rise to several moiré patterns. On the other hand, if the graphene is grown on Ru(0001)[4] or Rh(111)[5], there occurs an hybridization of the graphene π and the metallic d bands[1]. Because of this strong coupling, only one moiré pattern was expected. In the case of graphene on Rh(111), this structure is formed by (12x12) C atoms aligned with (11x11) Rh(111).

In this study we present, for the first time, the growth of multidomain graphene on Rh(111) under ultra-high vacuum (UHV) conditions by means of STM. Many different unexpected moiré patterns were observed on this reactive metal surface. These unusual structures, corresponding to smaller periodicities than the normal (12x12) C moiré, have been modeled through atomic resolved data by comparison with the larger moiré (figure 1). Also, the apparent corrugation of all these structures has been studied and its dependence on the moiré lattice parameter has been analyzed.


Fig. 1. 15 x 15 nm2 atomically resolved STM image where two different moirés are observed (corresponding models are shown on the left). The moiré named as “0” is the aligned (12 x 12) C superstructure. The parameters of the new moiré (1) are shown (VS= 30 mV, IT= 19 nA)

M. Batzill, Surf. Sci. Rep. 67, 83, (2012) M. M. Ugeda, D. Fernández-Torre, I. Brihuega, P. Pou, A.J. Martínez-Galera, R. Pérez, and J.M. Gómez-

Rodríguez, Phys. Rev. Lett. 107, 116803, (2011) A. J. Martínez-Galera, I. Brihuega, and J. M. Gómez-Rodríguez, Nano Lett. 11, 3576, (2011) B. Borca, S. Barja, M. Garnica, M. Manniti, A. Politano, J. M. Rodríguez-García, J. J. Hinarejos, D. Farías, A. L.

Vázquez de Parga, R. Miranda, New J. Phys. 12, 093018 (2010) E. N. Voloshina, Y. S. Dedkov, S. Torbrugge, A. Thissen, M. Fonin, Appl. Phys. Lett. 100, 241606, (2012)

Mechanical Properties Of Graphene With Defects Created By Ion Bombardment

Guillermo López-Polín1, Cristina Gomez-Navarro

1,2, Vincenzo Parente

3, Francisco

Guinea3, Mikhail I. Katsnelson

4, Francesc Perez-Murano

5, Julio Gomez-Herrero

1,2

1 Dpto. de Física de la Materia Condensada, Universidad Autónoma de Madrid, 28049, Madrid, Spain. 2 Centro de Investigación de Física de la Materia Condensada, Universidad Autónoma de Madrid, 28049,

Madrid. 3 Instituto de Ciencia de Materiales, CSIC, 28049, Madrid, Spain 4 Radboud University Nijmegen,

Institute for Molecules and Materials, Heyendaalseweg 135, NL6525AJ 5 Instituto de Microelectrónica de Barcelona, CSIC, 08193 Bellaterra, Spain.

Pristine graphene sheets exhibits superior mechanical properties very promising for applications: they are very light, flexible, stiff, and strong [1]. One of the main problems for its applications is that the known routes to obtain graphene in large scale (CVD, Graphene oxide), produce layers with different kind of defects (grain boundaries, point defects). These defects have been demonstrated to lower the stiffness and strength of the layers [2, 3]. Unfortunately, the fact that these defects are created in a non-controlled manner during sample preparation prevents a systematic study of how the mechanical properties vary with the defects. Our approach in this work is to introduce defects in our membrane in a controlled manner by Ar+ ion bombardment, creating mainly atomic monovacancies. For a precise characterization of the defect type and density we use Raman spectroscopy and STM. Then we measure the variation of the stiffness and strength with defect density using AFM nanoindentations (Fig.1). Counter intuitively, we find that the stiffness of graphene increases with defect content until a

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vacancy content of ~0.2%, where it doubles its initial value. For higher irradiation doses the elastic modulus slowly decreases with defects inclusion. The initial increase in stiffness can be explained in the framework of statistical mechanics of 2D membranes, where the elastic coefficients are predicted to depend with the momentum of flexural modes [4]. In contrast to the elastic trend, the fracture strength decreases with defect density according to standard fracture continuum models.

C. Lee, X. D. Wei, J. W. Kysar, J. Hone, Science, 321 (2008), 385 C. Gomez-Navarro, M. Burghard, K. Kern, Nano Letters, 8 (2008), 2045 C. S. Ruiz-Vargas et al., Nano Letters, 11 (2011), 2259. J. A. Aronovitz, T. C. Lubensky, Physical Review Letters, 60 (1988), 2634

Uniaxial Strain Control of Metal Insulator Transitions in Sr2IrO4 thin films

L. López-Mir,1,2,* X.Martí,1,3,4 M. Paradinas,2 C.Ocal,2 G.Catalán,1,5 N.Domingo.1,6

1 ICN2 - Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193Bellaterra (Barcelona), Spain. 2Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus UAB, 08193 Bellaterra

(Barcelona), Spain. 3Institute of Physics ASCR, v.v.i., Cukrovarnická 10, 162 53 Praha 6, Czech Republic. 4Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Ke

Karlovu 5, 12116 Praha 2, Czech Republic. 5ICREA - Institucio Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain. 6CSIC - Consejo Superior de Investigaciones Cientificas, ICN2 Building ,08193

Bellaterra (Barcelona), Spain

Recent studies suggest that manipulation of the epitaxial strain can tune the electronic structure of the Jeff = ½ Mott insulator Sr2IrO4, which is a transition metal oxide that exhibits an exotic insulating state [1,2]. When thin films are grown on a substrate the mismatch between the lattice constant of the substrate and lattice constant of the thin film material induces an in-plane strain in order to achieve epitaxial growing. The in-plane lattice mismatch between Sr2IrO4 and the substrates can exert tensile or compressive strains to the film. On the other hand, mechanical stimuli induced by the tip of an atomic force microscopy (AFM) is the basis for the generation of different types of phenomenologies, from flexoelectric fields that can lead to mechanical writing in ferroelectric materials [3] to piezochemical effects due to the dynamics in ionic systems [4].

In this work, we present a novel technique to induce an insulator-to-metal transition by applying uniaxial pressure to the material through an Atomic Force Microscope (AFM) tip. We


achieve the reversible mechanical control of dielectric gap in a semiconductor oxide that lead to metal-insulator transitions induced by uniaxial stress, demonstrating that local electronic structures can be locally changed by applying uniaxial pressure through an AFM tip. The AFM tip also acts as a sensor and transport measurements through the AFM tip are done through different approaches. In all cases the experimental setup consist of the sample and tip placed in series resulting in a capacitor where the tip is the top electrode and an LSMO thin film substrate between SIO and STO is the bottom electrode. While the features of the I(V) for the lowest applied forces resemble those of a semiconductor, linear Ohmic behavior is achieved for increasing forces with increasing slopes. From the obtained results, we observed a significant and reversible decrease of the resistance of the Sr2IrO4 thin film as a function of increasing mechanical loading force on the AFM tip. We attribute this behaviour to an insulator-to-metal transition caused by pressure induced changes in the Ir-O-Ir bond angle in the plane which produce a closure of the band gap.

Fig 1. Resistance as a function of the applied forcé through an AFM onto Sr2IrO4

C. Rayan Serrao, et al., Physical Review B 87, (2013) 085121. J. Nichols, et al.,Appl. Phys. Lett. 102, (2013) 141908. H. Lu, et al., Science 336, 59 (2012). Y. Kim, et al.,Nanoletters 13 (2013) 4068.

In Situ High Pressure STM Imaging Of A Fischer-Tropsch Cobalt Catalyst

Violeta Navarro1, M.A. van Spronsen

1, J.W.M. Frenken

1

1 Kamerlingh Onnes Laboratory. Leiden University. Leiden, The Netherlands.

Real dynamic systems, for example catalysts, can only be understood when they are examined under realistic working conditions. Otherwise the physico-chemical processes governing the system might not be the same. Although catalysts’ have largely been studied with traditional surface science techniques, those are typically used under vacuum conditions- very different to the real industrial ones. The difference in pressure, the “pressure gap”, between those vacuum studies and the industrial ones can be up to 13 orders of magnitude. Even though the studies in vacuum can be very revealing [1], the “pressure gap” leads to dramatic differences between laboratory and industrial systems. We need to study catalytic systems in situ since reaction mechanisms and changes on the catalyst surface during the reaction [2] can be very different under the fore mentioned pressures. In our lab we follow catalysts at the atomic scale reproducing the conditions of pressure and temperature used in the industry. We do this using

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a scanning tunneling microscope (STM) which can work under high pressures (up to 6 bar) and temperatures (up to 320°C) [2, 3]. The STM tip is inside a small gas flow reactor placed in a UHV chamber. Traditional surface science techniques are used to prepare and characterize the samples down to the atomic level, before exposing them to reaction conditions. We can visualize the structural changes on the surface of the catalyst during the reaction. Simultaneously we use mass spectrometry to detect the gaseous products of the reaction to correlate them with structural changes. As a model catalyst, we have used a single crystal of cobalt to study the Fischer-Tropsch synthesis (FTS). This catalytic reaction produces hydrocarbons of different lengths from a mixture of CO and H2, like octanes, used as fuel. This reaction is of extreme industrial relevance but the fundamental mechanisms are still not known [4]. We have got some insight into the catalyst in action. We have observed several changes on the very dynamic cobalt surface at the atomic scale during the reaction. Among others, islands with internal periodicity appear on the surface. We believe that those are molecules produced during the reaction that self assemble on the surface depending on their length forming regular arrays and they eventually desorb.

G. Ertl. Angewandte Chemie International Edition, 52, 1, 52–60, (2013). Y.D.Yin, et al., Science, 304, 5671. 711 (2004). R. Schaub, et al.. Phys. Rev. Let. 87, 26 (2001).

B. L.M. Hendriksen, et al., Topics in Catalysis, 36, 1–4 (2005). C.T. Herbschleb et al. Rev. Sci. Instr. Submitted. J. Wilson et al., J. Phys. Chem. 99, 7860 (1995).

Nanophotoactivity Of Porphyrin Functionalized ZnO Solar Cells

Elisa Palacios-Lidón1, David F. Pickup

2, Eneko Azaceta

3, Jaime Colchero

1, Ramón Tena-

Zaera3, Celia Rogero

2

1 Centro de Investigación en Optica y Nanofísica, Universidad de Murcia, Murcia, Spain 2 Centro de Física

de Materiales (CSIC-UPV/EHU,) San Sebastian, Spain 3 Energy Division, IK4-CIDETEC, San Sebastian, Spain

Dye-sensitized solar cells (DSCs) are seen as promising candidates for the next generation of inexpensive but efficient solar-energy conversion. During the last decade, ZnO has become an appealing material for applications in optoelectronic devices due to its unique properties such as wide band gap, strong room-temperature luminescence; and, most importantly, low cost. Recently, it has been envisaged as a possible alternative to the wide-band-gap TiO

2 based

DSCs. However ZnO DSCs efficiencies (7.5%) are still modest compared to those of TiO2-based devices (13%) [1,2]

The aim of this work is to study the nanophotoactivity of polycrystalline ZnO samples functionalized with porphyrin IX (H2PPIX) dye. The electrostatic response of the samples has been studied in darkness and under illumination using KPM and ESFM. From these measurements the charge photogeneration and dye-ZnO charge transfer are inferred. Fig.1 shows the electrooptical behavior of the bare and H2PPIX functionalized ZnO samples when the illumination is performed at the Soret band of the porphirine (λ=400nm).In this work we will discuss the fact that whilst no significant changes are observed in the morphology the electrostatic properties drastically change between bare and functionalized surfaces.


N. Memarian, I. Concina, A. Braga, S. M. Rozati, A. Vomiero and G. Sberveglierit, Angew. Chem. Int. Ed. 50,

12321 (20011) S. Mathew, A. Yella, P. Gao1, R. Humphry-Baker, B. F. E. Curchod, N. Ashari-Astani, I. Tavernelli, U.

Rothlisberger, Md. K. Nazeeruddin and Michael Grätzel, Nature Chemistry DOI: 10.1038/NCHEM.1861 (2014)

Study Of Polymer Relaxation Dynamics By Means Of AFM Based Dielectric Spectroscopy

L.A.Miccio1,2

, G.A.Schwartz2, A.Alegría

1, J.Colmenero

1,2,3

1 Universidad del País Vasco. Donostia-San Sebastián. 2 Material Physics Center 3 Donostia International Physics Center

Polymeric materials present dielectric dispersion and absorption phenomena in the 10-6-1012 Hz range due to the reorientational motion of molecular dipoles and/or the translational motion of ions/ trapped charges[1]. The systematic study of these phenomena through broadband dielectric spectroscopy (BDS) reveals information of structure and dynamics of these materials, therefore having great technological and scientific relevance. A stage has been reached where the foundations of BDS are well established in terms of a large number of scientific works for the dielectric behavior of dipolar materials and moderately-conductive systems[1]. However, in the l ast few years the growing interest in nanostructured materials highlighted the need of measurements with spatial nanometer resolution, something that is missing in BDS. In this sense, the use of atomic force microscopy (AFM) as a tool for providing spatial resolution to the study of dielectric relaxation dynamics appears as the natural extension of the BDS studies[2-5]. In this work we present a complete characterization of molecular and collective dipolar fluctuations in polymeric materials by means of AFM based dielectric spectroscopy. In particular, we focus our analysis in technologically relevant relaxation processes in different environments i.e., segmental relaxations in immiscible blends interfaces, polarization processes in nanostructured polymer interfaces, among others. We propose simple models to quantitatively relate the dielectric losses of the materials with the detected phase between the electrical excitation and the AFM probe oscillation.

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Figure 1. Left: electrical phase image of a PS/PVAc blend (25/75 wt %), acquired at 5 kHz and 350K. Red areas show the places where the PVAc segmental relaxation takes place with a timescale comparable to the reciprocal of the excitation frequency, therefore providing the contrast with PS areas (blue). Right: relaxation spectra obtained on PVAc locations at different temperatures (red dashed line stands for the image excitation frequency).

F. Kremer and A. Schonhals, Broadband Dielectric Spectroscopy (Springer-Verlag, New York, 2003). P. S. Crider and N. E. Israeloff, Nano Letters 6, 887 (2006). P. S. Crider, M. R. Majewski, J. Zhang, H. Oukris, and N. E. Israeloff, Applied Physics Letters 91, 013102 (2007). C. Riedel, R. Arinero, P. Tordjeman, M. Ramonda, G. Lévêque, G. A. Schwartz, D. G. De Oteyza, A. Alegria, and

J. Colmenero, J. Appl. Phys. 106, 024315 (2009). G. A. Schwartz, C. Riedel, R. Arinero, P. Tordjeman, A. Alegría, and J. Colmenero, Ultramicroscopy 111, 1366

(2011).

A single-molecule approach to study dynamics of DNA helicases by applying magnetic forces

Carolina Carrasco1, Neville Gilhooly

2, Mark S. Dillingham

2, and Fernando Moreno-

Herrero1.

1Centro Nacional de Biotecnología, CSIC, Campus UAM, Darwin 3, 28049, Cantoblanco, Madrid, Spain 2Dept. of Biochemistry, School of Medical Sciences, University of Bristol, University Walk, Bristol, BS8

1TD, UK

Single-molecule manipulation and imaging techniques offer high potential to investigate DNA break repair reactions in new ways, providing information that is inaccessible to conventional ensemble experiments. Here, Magnetic Tweezers (MT) has been used to follow in real time the translocation of helicases at the single molecule level. In the MT setup, a single molecule of DNA is tethered between a streptavidin-coated micrometer-size magnetic bead (SA-bead) and the bottom glass surface of a liquid cell by Dig-Anti-Dig links. Vertical translation and rotation of the magnets above the liquid cell induce stretching and torsion forces on the DNA molecule, respectively. By linking streptavidin-coated paramagnetic beads to biotinylated helicase, we were able to apply a force against the action of the motor protein and thus monitor the helicase activity (Fig.1.A). After arrival of ATP, helicase starts to translocate along the DNA dragging down the microscopic bead to which is attached. The magnetic beads are visualized using an inverted optical microscope (Fig.1.B) and the bead position (DNA end-to-end distance) is recorded in real time by video-microscopy. We have studied the processivity and


translocation rate of a helicase-nuclease protein involved in the DNA repair as a function of the applied force, DNA sequence, temperature and ATP concentrations on damaged or undamaged DNA. In the fig.1.C a typical single translocation trace is shown.

XPEEM And LEEM: State Of The Art Surface Characterization Tools At ALBA

Lucia Aballe1, Michael Foerster

1

1 ALBA Synchrotron Light Facility, 08290 Cerdanyola del Vallès, Barcelona (Spain)

The ALBA Synchrotron Light Facility (Barcelona) is based on a 3 GeV, low-emittance storage ring which feeds intense photon beams to different beamlines dedicated to basic and applied research in many fields, e.g. condensed matter physics, material science, chemistry, biology and medical sciences.

Among the instruments accessible to external users there is a combined X-ray PhotoEmission Electron Microscope (XPEEM) and Low Energy Electron Microscope (LEEM), in operation since 2012.

The XPEEM is fed by the variable polarization CIRCE undulator beamline (100-2000 eV photon energy), and permits imaging surfaces with chemical, structural, and magnetic sensitivity down to a lateral spatial resolution of 20 nm. XPEEM has applications in a wide variety of fields such as surfaces and interfaces, nanostructures, or micro-magnetism. Contrast mechanisms based on x-ray absorption (including dichroism) as well as on photoemission are available, thanks to an imaging electron energy analyzer with resolution below 0.2eV. Microspot-diffraction (LEED and photoelectron diffraction) and numerous in situ preparation facilities (evaporators, high temperature annealing, gas dosage, sputter gun,…) are available in the same instrument,

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making it a true multitechnique station for the surface characterization of heterogeneous systems.

An overivew of the XPEEM-LEEM experimental capabilities and application examples will be presented.

Nanoscale IR Spectroscopy, Dielectric Function Mapping And Depth Profiling With Near-field Microscopy

Alexander Govyadinov1, Stefan Mastel

1, Federico Golmar

2, Andrey Chuvilin

1,4, P. Scott

Carney3, Rainer Hillenbrand

1,4

1 CIC Nanogune Consolider, Donostia-San Sebastian, Spain 2 I.N.T.I.-CONICET and ECyT-UNSAM, San

Martin, Argentina 3 ECE Dept. and Beckman Institute, U. of Illinois atUrbana-Champaign, Urbana, USA 4 IKERBASQUE, Basque Foundation for Science, Bilbao, Spain

Scattering-type scanning near-field optical microscopy (s-SNOM) is a powerful optical technique for nondestructive spectroscopic imaging with deep subwavelength resolution [1]. s-SNOM is typically based on the atomic force microscopy (AFM), in which the scanning probe is illuminated externally and the backscattering is detected. The sharp probe concentrates light at its apex, thus serving as a strong nanoscopic illumination source for the sample. The light scattered by the probe depends on the local sample composition, therefore providing means for its investigations at the nanoscale.

By employing broadband infrared (IR) illumination source, s-SNOM has demonstrated the capability of performing nanoscale FTIR spectroscopy of samples (nano-FTIR) [2]. We have further shown that for weak molecular oscillators (i.e. polymers, biological matter, etc.), nano-FTIR spectra can be directly compared to the far-field FTIR databases, allowing for the chemical identification of sample components with unprecedented spatial resolution [3].

In this work we demonstrate the ability of IR s-SNOM and nano-FTIR to quantitatively measure local dielectric function of thin films samples composed of weak oscillators [4]. Our approach is based on a theoretical description of s-SNOM scattering process that allows for an analytic inversion of s-SNOM data, i.e. analytically solves the near-field scattering problem to obtain the solution for the dielectric permittivity. Such inversion does not require fitting or minimization procedures, thus providing high speed and robust performance. It yields the same information about the sample as typically obtained by far-field ellipsometry with an important advantage of providing nanoscale spatial resolution even at IR frequencies.

We further show that simultaneously with the dielectric permittivity, the film thickness can be recovered from s-SNOM data without relying on measurements of topography [5]. In other words, our work enables the quantitative nanoscale-resolved in-depth profiling of dielectric properties of heterogeneous samples in which the topography does not correlate with the chemical or optical properties. It presents an important advance towards complete three-dimensional near-field tomography and opens new frontiers for chemometrics, materials and bio sciences.


T. Taubner, R. Hillenbrand, and F. Keilmann, Appl. Phys. Lett. 85, 5064 (2004) F. Huth, M. Schnell, J. Wittborn et al, Nat. Mater. 10, 352 (2011) F. Huth, A. Govyadinov, S. Amarie et al, Nano Lett. 12, 3973 (2012) A. Govyadinov, I. Amenabar, F. Huth et al, J. Phys. Chem. Lett. 4, 1562 (2013) A. Govyadinov, S. Mastel, F. Golmar et al, submitted to ACS Nano

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Friday, August 29, 2014, San Sebastián, Spain 45

A step further for better understanding of molecular junctions and highresolution SPM images

P. Jelinek

Institute of Physics of the AS CR, Prague, Czech Republic

The recent progress in Scanning Probe Microscopy provided unprecedented atomic resolution of single molecules [1,2]. What more, simultaneous AFM/STM measurements allow precise control of both mechanical and transport properties on single molecular junctions [3]. In first part of the talk, I will a simple mechanistic model of STM/AFM imaging mechanism of organic molecules with functionalized probe, which takes into account relaxation of the molecular probe due to tip-sample interaction. We will demonstrate, that the model is able to produce very well not only experimentally observed intra and intermolecular contrast but also its evolution upon the tip approach, comparing directly theoretical and experimental AFM/STM images of PTCDA on Au(111). In second part, I will discuss bias dependent simultaneous nc-AFM/STM measurements on single molecular junction, which reveals presence of current driven force acting in molecular junction. I will also discuss the theoretical understanding of these measurements.

L. Gross et al., Science 325,1110 (2009) C. Weiss et al., Phys.Rev.Lett. 105, 086103 (2010) N. Fournier et al Phys. Rev. B84, 035435 (2011).

Bandgap Engineering Of Bottom-Up Synthesized Graphene Nanoribbons

Dimas G. de Oteyza1,3

, Yenchia Chen1, Ting Cao

1, Chen Chen

1, Zahra Pedramrazi

1,

Danny Haberer1, Felix R. Fischer1,2, Steven G. Louie1,2, Michael F. Crommie1,2

1 University of California at Berkeley, Berkeley, USA 2 Lawrence Berkeley National Laboratory, Berkeley,USA 3 Centro de Fisica de Materiales CSIC-UPV/EHU, San Sebastian, Spain

A prerequisite for future graphene nanoribbon (GNR) applications is the ability to finetune the electronic band gap of GNRs. Such control requires the development of fabrication tools capable of precisely controlling width and edge geometry of GNRs at the atomic scale. With the advent of bottom-up synthesized GNRs increasingly high hopes are being placed on this approach and the resultant atomically precise GNRs. We report a controlled GNR band gap modification via covalent self-assembly of different species of molecular precursors that yield n = 13 and n = 7 armchair GNRs (where n stands for the number of C dimer lines across the ribbon width)[1]. Scanning tunneling microscopy and spectroscopy (STM & STS) reveal that n = 13 armchair GNRs have a band gap of 1.4 eV, 1.2 eV smaller than the gap determined for n = 7 armchair GNRs. It is predicted that further GNR bandgap engineering may be realized utilizing combinations of two or more different building blocks that vary width or doping at desired positions (in analogy to the well-established bandgap engineering in inorganic materials)[2]. We apply this same concept combining both types of precursors, demonstrating bottom-up


synthesis of width modulated GNRs. We study the resultant junctions with STM and STS, and identify distinct electronic structures in individual GNR segments. We have additionally performed first-principles calculations that further support our experimental results.

Y.-C. Chen, D. G. de Oteyza, Z. Pedramrazi, C. Chen, F. R. Fischer, M. F. Crommie, ACS Nano 2013, 7, 6123 H. Sevinçli, M. Topsakal, S. Ciraci, Phys. Rev. B 2008, 78, 245402

General Force Reconstruction Method for Amplitude Modulation Force Microscopy Experiment

A.F. Payam, D. Martin-Jimenez , R. Garcia


E-mail: [email protected]

Amplitude Modulation Atomic Force Microscopy (AM-AFM) is the most widely used technique for nanoscale characterization of materials and surfaces in the air and liquid environments. High detection or sensitivities and smaller lateral forces with respect to contact AFM are the advantages of the dynamic modes of AFM. However, in AM-AFM experiments the interaction force is not direct observable [1].

Several methods have been proposed to recover the force in AM-AFM with the use of a unique frequency of excitation. These methods are valid either for small or large amplitudes relative to the indentation length [2]-[4]; or expand the force in terms of polynomials which require determination of a large number of parameters which makes them complicated for practical implementation [2], [5]. To overcome the above limitations, we develop a general method to transform the observables in amplitude modulation force microscopy into quantitative force measurements. The force reconstruction algorithm has been deduced on the assumption that the observables (amplitude and phase shift) are slowly varying functions of the average tip-surface distance. This method is general because is valid for small and large amplitudes; operation in air and liquid, compliant and rigid materials, conservative and non-conservative interactions alike. Numerical analysis and experimental tests verify the accuracy and validity of the proposed method.

(a) AFM image of polystyrene (PS) and polyolefin elastomer (LDPE) blend. (b) Amplitude and phase shift versus z-piezo displacement on PS corresponding to black cross in a. (c) Force reconstruction of PS. (d) Amplitude and phase shift versus z-piezo displacement on LDPE corresponding to white cross in a. (e) Force reconstruction of LDPE.

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[1]. D. Platz, D. Forchheimer, E.A. Tholén and D.B. Haviland, Nat. Comm. 4, 1360 (2013). [2]. M. Lee and W. Jhe, Phys. Rev. Lett. 97, 036104 (2006). [3]. H. Holscher, U.D. Schwarz, int. J. Nonlinear Mech. 42, 608-625 (2007). [4]. A.J. Katan, M.H. van Es and T.H. Oosterkamp, Nanotech. 20, 165703 (2009). [5]. S. Hu and A. Raman, Nanotech. 19, 375704 (2008).

Adsorption Geometry Of Pentacene On TiO2 Anatase Surface Resolved By Intra-molecular Atomic Force Microscopy Imaging

Cesar Moreno1, Oleksandr Stetsovych

1, Milica Todorovic

2, Tomoko K. Shimizu

1, Rubén

Pérez2, Oscar Custance1

1 National Institute for Materials Science (NIMS), 1-2-1 Sengen Tsukuba, Ibaraki 3050047, Japan 2 Departamento de Física Teórica de la Materia Condensada, Universidad Autonoma de Madrid, E-28049

Madrid (Spain)

TiO2 is very promising material because it is stable, non-corrosive, environmentally friendly, abundant and cost- effective. Since most of the peculiar properties of TiO2 are surface-mediated, a deep understanding of the surface properties of this reducible oxide material is a critical issue to develop high-performance devices. Furthermore, pentacene is an archetypical organic small molecule broadly used in organic electronics devices. Here, we present a characterization of the morphology and electronic properties of this molecule deposited at submonolayer regime on the TiO2(101) anatase surface by combining Kelvin Probe Force Microscopy and simultaneous atomic force microscopy / scanning tunneling microscopy working with atomic resolution. Intra-molecular structure of planar pentacene was successfully achieved (Figure 1) simultaneously with the atomic resolution of the titanium dioxide surface, allowing us to put insight in the adsorption geometry (shape, size and relative position) of pentacene on TiO2 surface with atomic accuracy. These experimental results have been corroborated by first-principles calculations.

Figure 1

http://www.nature.com/ncomms/journal/v4/n1/ncomms2365/metrics#auth-1





Attractive Tip-sample Force Reconstruction For Dynamic Atomic Force Microscopy In Ambient Conditions

Albert Verdaguer1, Annalisa Calo

1, Carlo Alberto Amadei

2, Matteo Chiesa

2, Sergio

Santos3

1 Institut Català de Nanociencia i Nanotecnologia (ICN2), Bellaterra (Barcelona), Spain 2 Masdar Institute

of Science and Technology, Abu Dhabi, United Arab Emirates 3 Departament de Disseny i Programació de Sistemes Electrònics, UPC - Universitat Politècnica de Catalunya, Manresa (Barcelona), Spain

Since its advent and due its high spatial resolution, Atomic Force Micorscopy (AFM) has enabled probing single nanostructures, mapping heterogeneous compositional variation in surface properties or studying molecular interactions. Initially the AFM was developed to operate in the quasistatic or DC mode but dynamic modes of operation where introduced to reduce lateral forces while imaging and enhance versatility. In terms of nanoscale processes and properties, a main advantage of dynamic AFM modes over DC modes relates to their capacity to simultaneously probe both conservative and dissipative forces while tracking the topography for imaging. Conservative and dissipative forces provide mechanical and chemical information about samples at the nanometer scale. Force reconstruction maps in DC modes, i.e. quasistatic modes, suffer from stability resulting in so-called "jump-to-contact" where information for a range of distances is lost. Also the signal-to-noise ratio might be compromised by pink noise, i.e. noise is proportional to the inverse of the frequency. On the other hand, interpreting data acquired from the dynamic modes of operation requires detailed modeling and care as the tip follows a non-monotonic force trajectory during each oscillation cycle. We have applied a mathematical model to reconstruct, from simple amplitude and phase versus distance curves, the interaction forces between the AFM tip and a sample in ambient conditions [1]. We will show our results on the reconstruction of forces acting before mechanical contact between the tip and the sample occurs. That would include capillary forces [2], long-range van der Waals forces and forces arising from the formation of chemical bonds.

Figure a) Scheme of the possible interactions occurring between an AFM tip and a surface. b) Experimental reconstruction of the force (Fts) from amplitude (A) and phase variation as a function of tip-sample separation in dynamic AFM.

S. Santos, C. A. Amadei, A. Verdaguer, M. Chiesa. J. Phys. Chem. C 117 - 20, 10615 –10622 (2013) C. A. Amadei, S. Santos, S. O. Pehkonen, A. Verdaguer, M. Chiesa. J. Phys. Chem. C. 117 - 40,20819 –20815

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(2013)

Atomic Force Microscopy In High Vacuum: Experiments On Graphitic Surfaces

M. Jaafar1, G. López Polin

2, D. Martínez Martín

3, C. Gómez Navarro

2, J. Gómez Herrero

2

1 Instituto de Ciencia de Materiales de Madrid, ICMM- CSIC. Madrid, Spain 2 Departamento de Física de la Materia Condensada, Univerisdad Autónoma de Madrid, Madrid, Spain 3 Department of Biosystems

Science and Engineering ETH, Zurich, Basel,Switzerland

Atomic Force Microscopy (AFM) working in high vacuum (HV) conditions is a valuable technique due to its sensitivity and versatility. In this work we present different experiments in carbon-based materials. We use the HV-AFM to perform different experiments on graphitic surfaces like graphene and graphene oxide (GO). Graphene can be described as one-atom thick layer of graphite. For many applications, the interaction of graphene and GO with the supporting substrate and with adjacent layers plays a relevant role in properties such as adhesion, charge transfer [1], doping level etc. Furthermore, it is important to take into account the presence of atmospheric contaminants for a correct interpretation of experimental data [2]. Finally, we have studied the influence of a pressure difference onto the mechanical properties of suspended graphene membranes [3]. We have studied the diffusion through these membranes as a function of the kinetic diameter of the gas molecules [4] (Figure 1).

Figure 1. Suspended monolayer of graphene as a selective gas barrier.

M. Jaafar et al. Appl. Phys. Lett. 101, 263109 (2012) D. Martinez-Martin, et al. Carbon 61 33 –39 (2013) G. López – Polín et al. submitted M.Jaafar et al. in preparation.

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ABSTRACTS. POSTER PRESENTATIONS


List of Posters

P1 ...................................................................................................................................................................................................... 57

Graphene Growth On Pt(111) And Au(111) Using A MBE Solid Carbon Source ........................................................................ 57

Irene Hernández-Rodríguez, J. M. García, J. A. Martín-Gago, P. L. de Andrés, Javier Méndez ................................................ 57

P2 ...................................................................................................................................................................................................... 58

Quantum Interference In Tunneling Through A Molecular Kondo System .................................................................................. 58

I. Fernandez-Torrente, M. Ruby, T. R. Umbach, B. W. Heinrich, J. I. Pascual, K. J. Franke ...................................................... 58

P3 ...................................................................................................................................................................................................... 59

Mechanical Force Modulates the Unfolding Pathways of the Cold-Shock Protein B from Thermotoga Maritima ....................... 59

Jörg Schönfelder, Raul Perez-Jimenez, Victor Muñoz ................................................................................................................ 59

P4 ...................................................................................................................................................................................................... 60

Replication Initiation Proteins Studied With Atomic Force Microscopy ........................................................................................ 60

Maria Eugenia Fuentes-Perez, Katarzyna Wegrzyn, Igor Konieczny, Fernando Moreno-Herrero .............................................. 60

P5 ...................................................................................................................................................................................................... 61

Design an Iterative Learning Observer to Reconstruct the Interaction Force in AM-AFM ........................................................... 61

F. Payam, D. Martin-Jimenez, R. Garcia ..................................................................................................................................... 61

P6 ...................................................................................................................................................................................................... 61

STM And Nc-AFM Investigation Of Submonolayer Copper Oxide Structures ............................................................................. 61

Carmen Ocal, Esther Barrena, Sonia Matencio ........................................................................................................................... 61

P7 ...................................................................................................................................................................................................... 62

Structural Control Of Bridge State Resonances In Single Molecular Junctions .......................................................................... 62

Carly Brooke, Andrea Vezzoli, Simon J. Higgins, Linda A. Zotti, Juan Jose Palacios, Richard J. Nichols ................................. 62

P8 ...................................................................................................................................................................................................... 63

Magnetic Force Microscopy Of Focused Ion Beam Patterned Co Antidot Arrays ....................................................................... 63

Andreas Kaidatzis, Rafael Pérez del Real, Raquel Alvaro, Jose V. Anguita, Manuel Vazquez, José Miguel García-Martín ..... 63

P9 ...................................................................................................................................................................................................... 64

Investigating Subsurface Boron Dopants In Si(111)-(√3x√3) R30° Using Simultaneous Nc-AFM/STM And DFT ..................... 64

Jan Berger, Evan J. Spadafora, Pingo Mutombo, Mykola Telychko, Martin Ondráček, Martin Švec, Alastair McLean, Pavel Jelínek .......................................................................................................................................................................................... 64

P10 .................................................................................................................................................................................................... 65

Probing The Fermi Surfaces Of The Two-band Superconductor Lead ....................................................................................... 65

B. W. Heinrich, M. Ruby, J. I. Pascual, K. J. Franke .................................................................................................................... 65

P11 .................................................................................................................................................................................................... 66

Boron- and Nitrogen-doped Multiwall Carbon Nanotubes Studied By Kelvin Probe Microscopy ................................................ 66

J. F. González-Martínez, J. Abad, J.-S. Park, J.-M. Lee, S.-O. Kim, J.-S. Kim, A. Urbina and J. Colchero ................................ 66

P12 .................................................................................................................................................................................................... 67

Calibration of Normal Force using non-destructive Dynamic Force Microscopy ......................................................................... 67

Juan Francisco González Martínez, Jaime Colchero Paetz ........................................................................................................ 67

P13 .................................................................................................................................................................................................... 68

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Modelling dissipation in Dynamic Scanning Force Microscopy as a function of tip-sample distance .......................................... 68

Juan Francisco González Martínez, Jaime Colchero Paetz ........................................................................................................ 68

P14 .................................................................................................................................................................................................... 69

Structure–performance Relationships In Solution-processed Organic Solar Cells Based On Acceptor-substituted S,N Heteroacenes ............................................................................................................................................................................... 69

Marta Urdanpilleta, Hannelore Kast, Amaresh Mishra, Gisela L. Schulz, Elena Mena-Osteritz, Peter Baeuerle ....................... 69

P15 .................................................................................................................................................................................................... 70

Ether Groups And Acyl-chain Branching Reduce Nanomechanical Resistance Of Phospholipid Bilayers: A Force Spectroscopy Study ............................................................................................................................................................................................ 70

Aritz B. García-Arribas, Jesús Sot, Daniel Balleza, Kepa Ruiz-Mirazo, Alicia Alonso, Félix M. Goñi ......................................... 70

P16 .................................................................................................................................................................................................... 71

Understanding Transverse Shear Microscopy In Crystalline Organic Layers ............................................................................. 71

A. Pérez-Rodríguez, A. Fernández, C. Ocal, E. Barrena............................................................................................................. 71

P17 .................................................................................................................................................................................................... 72

α-Fe2O3(0001) Surface As A Model Catalyst: Morphology And Electronic Structure ................................................................ 72

Sara Barja, Alexander Weber-Bargioni, Miquel Salmerón ........................................................................................................... 72

P18 .................................................................................................................................................................................................... 73

Surface Charge Differentiation of Avidin and Streptavidin By AFM-Force Spectroscopy ........................................................... 73

L. Almonte, E. López-Elvira, A.M. Baró ....................................................................................................................................... 73

P19 .................................................................................................................................................................................................... 74

Amplitude modulation dynamic force microscopy for stable imaging of samples with heterogeneus in liquids .......................... 74

Lisa Almonte, Arturo M. Baró, Jaime Colchero ............................................................................................................................ 74

P20 .................................................................................................................................................................................................... 75

Detecting charging effects in single molecules by nc-AFM.......................................................................................................... 75

Fabian Schulz, Christian Lotze, Martina Corso, Isabel Fernandez-Torrente, Katharina J. Franke, J. Ignacio Pascual ............. 75

P21 .................................................................................................................................................................................................... 76

Two Dimensional Gadolinium Alloys On Noble Metal Surfaces .................................................................................................. 76

Alexander Correa, Bin Xu, Matthieu Verstraete, Lucia Vitali ....................................................................................................... 76

P22 .................................................................................................................................................................................................... 77

Elastic-Plastic Switch Of Tomato Bushy Stunt Virus Particles .................................................................................................... 77

A. Llauró, E. Coppari, F. Imperatori, A.R. Bizzarri, L. Santi, S. Cannistraro, P. J. de Pablo ....................................................... 77

P23 .................................................................................................................................................................................................... 77

Studying The Mechanical Behavior Of Cardiac Stem Cells By Means Of Atomic Force Microscope ......................................... 77

R. Daza, N. Marí, G. R. Plaza, B. G. Gálvez, A. Bernal, G. V. Guinea, J. Pérez-Rigueiro, M. Elices ......................................... 77

P24 .................................................................................................................................................................................................... 78

Exploring Van Der Waals Interaction For Organic Macromolecules On Metal Surfaces ............................................................. 78

Ane Sarasola, Mikel Abadía, Rubén González -Moreno, Celia Rogero, Aran Garcia-Lekue ...................................................... 78

P25 .................................................................................................................................................................................................... 79

Moirés on Graphene/Pt(111): low temperature NCAFM measurements and first-principles calculations ................................... 79

M. Ellner, B. de la Torre, P. Pou, N. Nicoara, J. M. Gómez-Rodríguez, R. Pérez ....................................................................... 79


P26 .................................................................................................................................................................................................... 80

Magnetic Domain Structures In Single Modulated FeCoCu Nanowires ...................................................................................... 80

O. Iglesias-Freire, E. Berganza, C. Bran, M. Vazquez, A. Asenjo ............................................................................................... 80

P27 .................................................................................................................................................................................................... 81

Donor-acceptor Interactions At Solid Surfaces Controlled By Charge Transfer .......................................................................... 81

Koen Lauwaet, J. Rodríguez-Fernández, R. García, M. A. Herranz, N. Martín, J. M. Gallego, R. Otero, R. Miranda ................ 81

P28 .................................................................................................................................................................................................... 82

Local Electrical Properties Of Double Terminated La0.7Sr0.3MnO3 Films ................................................................................. 82

Laura López-Mir, José Cisneros, Carmen Ocal, Lluís Balcells, Benjamín Martínez, Laura López-Mir ....................................... 82

P29 .................................................................................................................................................................................................... 82

The Mode Of Growth And Magnetic Properties Of Ultrathin Co Films Grown On The Curved Pd(111) And Curved Ni(111) .... 82

A. Magaña, M. Ilyn, L. Fernández, J. E. Ortega, F. Schiller ........................................................................................................ 82

P30 .................................................................................................................................................................................................... 83

Neural Signatures Protocol In Artificial Neural Networks Used To Characterize The Electrostatic Signal In Conductive Thin Films ............................................................................................................................................................................................. 83

Elena Castellano-Hernández, Juan José Sáenz Gutiérrez, Sacha Gómez................................................................................. 83

P31 .................................................................................................................................................................................................... 84

Towards An AFM Study Of The Interaction Of Pseudomonas Aeruginosa With Multivalent Glycoclusters ................................ 84

F. Zuttion, D. Sicard, C. Ligeour, Y. Chevolot, F. Morvan, A. Imberty, G. Vergoten, S. Vidal, J.J. Vasseur, E. Souteyrand, M. Phaner-Goutorbe ......................................................................................................................................................................... 84

P32 .................................................................................................................................................................................................... 85

Surface Characterization Of PEGylated Self-assembled Monolayers On Gold For Biosensors Applications ............................ 85

A. Garnier, F. Zuttion, F. Palazon, Y. Chevolot, E. Laurenceau, G. Grenet, C. Botella, E. Souteyrand, M. Phaner-Goutorbe .. 85

P33 .................................................................................................................................................................................................... 86

Sublattice localized electronic states in atomically resolved graphene-Pt(111) edge-boundaries .............................................. 86

P. Merino, L. Rodrigo, A. L. Pinardi, J. Méndez, M. F. López, P. Pou, R. Pérez, J. A. Martín-Gago .......................................... 86

P34 .................................................................................................................................................................................................... 87

Quantum Capacitance and Electromigration: A Theoretical Approach ....................................................................................... 87

C. Salgado, J.J. Palacios ............................................................................................................................................................. 87

P35 .................................................................................................................................................................................................... 88

Domain overlap in Ni/Cu/Ni films with perpendicular magnetization: role of defects and ferromagnetic coupling ...................... 88

Miguel Ciria, Edna Corredor, David Coffey, José Luis Diez-Ferrez and José Ignacio Arnaudas ............................................... 88

P36 .................................................................................................................................................................................................... 89

Characterization Of Trimethylamonium-based Ionic Liquid Surfaces With Scanning Force Microscopy .................................... 89

Jaime Colchero, Jesús Sánchez-Lacasa, Pedro Lozano, Juana M. Bernal ................................................................................ 89

P37 .................................................................................................................................................................................................... 90

Manipulation Of The Electronic Structure In A Ruthenium Complex By An STM/AFM Tip ......................................................... 90

Marten Piantek, David Serrate, Jose Ignacio Pascual, Ricardo Ibarra ........................................................................................ 90

P38 .................................................................................................................................................................................................... 90

Temperature Controlled Formation Of Metal-organic Assemblies On Surfaces.......................................................................... 90

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Marten Piantek, David Serrate, Jose Ignacio Pascual, Ricardo Ibarra ........................................................................................ 90

P39 .................................................................................................................................................................................................... 91

The Verge Of Antiferromagnetic RKKY Order Among Individual Kondo Impurities .................................................................... 91

María Moro-Lagares, Marten Piantek, M. Ricardo Ibarra, José I. Pascual, David Serrate .......................................................... 91

P40 .................................................................................................................................................................................................... 92

Substrate/nanodot Exchange Coupling For Co Nanodot Arrays Grown On Rare Earth–Au (111) Based Nanotemplates ......... 92

L. Fernández, M. Blanco-Rey, M. Ilyn, L. Vitali, A. Magaña, A. Correa, P. Ohresser, J.E. Ortega, A. Ayuela, F. Schiller .......... 92

P41 .................................................................................................................................................................................................... 92

Ultra High Vacuum PVD Graphene growth on Cu-foils from a C60 carbon source: growth and characterization ....................... 92

J.Azpeitia, G. Otero-Irureta, F. J. Mompeán, B. Sánchez, M.García-Hernández, J. A. Martín-Gago, C. Munuera, M. F. López 92

P42 .................................................................................................................................................................................................... 93

Unusual Surface Faceting Induce by Metal Organic Complexes ................................................................................................ 93

M. Abadia, R. González-Moreno, A. Sarasola, G. Otero, A. Verdini, L. Floreano, A. Garcia-Lekue, and C. Rogero ................ 93

P43 .................................................................................................................................................................................................... 94

Search For A Gap-less Dangling Bond Wire. .............................................................................................................................. 94

Mads Engelund, Daniel Sanchez-Portál, Thomas Frederiksen, Aran Garcia-Lekué ................................................................... 94

P44 .................................................................................................................................................................................................... 95

On-surface chemistry: cyclodehydrogenation of PAH catalyzed by metal surfaces. ................................................................... 95

I. Palacio, A.L. Pinardi, G. Otero-Irurueta, J.I. Martinez, M.F. López, J. Méndez, J.A. Martín-Gago ........................................ 95

P45 .................................................................................................................................................................................................... 96

Substrate-Induced Stabilization And Reconstruction Of Zigzag Edges In Graphene Nanoislands On Ni(111) .......................... 96

M. Olle, A. García-Lekue, D. Sánchez-Portal, J.J. Palacios, A. Mugarza, G. Ceballos, P. Gambardella ................................... 96

P46 .................................................................................................................................................................................................... 97

Adsorption site dependence of vibrational excitations of molecular hydrogen ............................................................................ 97

E.Carbonell, M. Corso, J. Li, M. Borinaga, J.I. Pascual ............................................................................................................... 97

P47 .................................................................................................................................................................................................... 98

2D To 1D Transition Of Surface States Investigated On Bismuth Curved Crystals .................................................................... 98

Jorge Lobo-Checa, Federico Mazzola, Luca Barreto, Frederik M. Schiller, Justin W. Wells, Nicholas C. Plumb, Johan Adell5, Philip Hofmann, J. Enrique Ortega............................................................................................................................................... 98

P48 .................................................................................................................................................................................................. 100

A Toolbox For Controlling Quantum States In Organic Monolayers .......................................................................................... 100

Bernhard Kretz, David A. Egger, Egbert Zojer ........................................................................................................................... 100

P49 .................................................................................................................................................................................................. 100

Cementing Proteins Provide Extra Mechanical Stabilization To Viral Cages ............................................................................ 100

M. Hernando-Pérez, S. Kruse, E. Nakatani, C. E. Catalano, P.J. de Pablo1 ............................................................................. 100

P50 .................................................................................................................................................................................................. 101

Doping Of The Surface Of A Topological Insulator With Co Adatoms ....................................................................................... 101

M.C.Martínez-Velarte, M. Moro-Lagares, Trevor M. Riedemann, Thomas A. Lograsso, L. Morellón, M.R. Ibarra, D. Serrate . 101

P51 .................................................................................................................................................................................................. 102


Probing the magnetic interaction between single Cr atoms ....................................................................................................... 102

Zsolt Majzik, José Ignacio Pascual ............................................................................................................................................ 102

P52 .................................................................................................................................................................................................. 103

Are Textbooks Always Right? An AFM Search For Protein Packing Defects In Viruses........................................................... 103

Aitziber Eleta-Lopez, Alba Centeno, Amaia Pesquera, Amaia Zurutuza, Christina Wege, Alexander M. Bittner ..................... 103

P53 .................................................................................................................................................................................................. 104

A Theoretical DFT Study Of Unusual Moiré Patterns In The Graphene/Rh(111) System ......................................................... 104

Ana Martín-Recio, Antonio J.Martínez-Galera, José María Gómez-Rodríguez, Carlos Romero-Muñiz, Pablo Pou, Rubén Pérez ................................................................................................................................................................................................... 104

P54 .................................................................................................................................................................................................. 105

DFT study of AFM metal oxide imaging modes: Towards atomic species identification ........................................................... 105

Diego R. Hermoso, Milica Todorović, Harry Mönig and Rubén Pérez ....................................................................................... 105

P55 .................................................................................................................................................................................................. 106

Curved Crystals: A different approach to Surface Science ........................................................................................................ 106

J. E. Ortega, R. González-Moreno, F. López-Geijo, Z. M. Abd-el-Fattah, J. Lobo-Checa, M. Corso, U. Aseguinolaza, A. Mugarza, A. L. Walter, A. Magaña, M. Ilyin, L.A. Miccio, M. Abadía, and F. Schiller ................................................................ 106

P56 .................................................................................................................................................................................................. 107

Characterization Of Mn0.006NbSe2 From Bulk To Few Layers ................................................................................................ 107

Alexandre Correa orellana, Carmen Munuera, Roberto Fabián Luccas, Mar García Hernández, Hermann Suderow, Federico Mompean ................................................................................................................................................................................... 107

P57 .................................................................................................................................................................................................. 107

A digital electronics for fast SPM ............................................................................................................................................... 107

I. Horcas, A. Gimeno, P. Ares, J. Gómez-Herrero ..................................................................................................................... 107

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P1

Graphene Growth On Pt(111) And Au(111) Using A MBE Solid Carbon Source

Irene Hernández-Rodríguez1, J. M. García

2, J. A. Martín-Gago

1, P. L. de Andrés

1, Javier

Méndez1

1 Instituto de Ciencia de Materiales de Madrid (CSIC), 28049, Madrid, Spain 2 MBE Lab, Instituto de Microelectronica de Madrid (CSIC), 28760 Madrid, Spain

Graphene is considered a prototype material with interesting technological applications and properties [1]. Preparation methods greatly varies from exfoliation mechanical transfer [2] (widely used in research laboratories), to Chemical Vapor Deposition (CVD) [3] (more appropriate for industrial applications). When this later method is used, the catalytic properties of the metallic substrate play a fundamental role during decomposition (cracking of C-H bonds) of hydrocarbons.

In this work, we present a Molecular Beam Epitaxy (MBE) method to obtain graphene [4] on Pt (111). This procedure uses evaporation of carbon atoms from a carbon solid-source in ultra-high vacuum conditions. We have tested the formation of graphene on several surfaces: from a well establish substrate as platinum, to substrates where graphene can be formed using innovative methods as gold [5]. For the characterization of the graphene layers we have used several in situ surface science techniques as low energy electron diffraction (LEED), auger electron spectroscopy (AES) and scanning tunneling microscopy (STM).

The successful evaporation of carbon has been probed on different substrates as platinum, HOPG, and gold. By annealing a Pt(111) and Au(111) surfaces up to 600ºC and 450ºC respectively during carbon evaporation, we have observed a characteristic LEED diagram attributed to graphene [6]. STM images (see figure) display long range ordering of carbon monolayers showing several moirés patterns characteristic of graphene on Pt(111) [7] and islands of dendrites of Au(111) [8], further proving the formation of graphene. This method opens up new possibilities for the formation of graphene on many different substrates with potential technological applications.

Figure 1: STM image of graphene on Pt(111) showing long range moirés patterns and atomic resolution (Bias Voltage = -35.7mV, Current set-point = 0.04nA).

Figure 2: STM image of graphene on Au(111) showing long dendritic islands at both sides of the steps. For this tip-state, graphene appears as a depression area (Bias Voltage = -12141.7mV, Current set-point = 4μA).

Castro Neto, A.H. et al., Rev. Mod. Phys., 81 (2009) 109. Geim, A.K. and Novoselov, K.S. Nature Mater., 6 (2007) 183.


Kim, K.S, et al., Nature, 457 (2009) 706-710. Garcia, J.M. et al., Solid State Commun. 152 (2012) 975-978. Martinez-Galera, A.J. et al., Nano Lett., 11 (2011) 3576. Sutter, P. et al., Phys. Rev. B, 80 (2009) 245411. Merino, P. et al., ACS Nano, 5 (2011) 5627. Nie, Shu et al., Phys. Rev. B, 85 (2012) 205406

P2

Quantum Interference In Tunneling Through A Molecular Kondo System

I. Fernandez-Torrente1, M. Ruby

1, T. R. Umbach

1, B. W. Heinrich

1, J. I. Pascual

2, K. J.

Franke1

1 Institut für Experimentalphysik, Freie Universität Berlin, Germany 2 CIC Nanogune, Donosti-San

Sebastián, Spain

The origin of the Kondo effect is understood as a scattering process between an unpaired spin located at a magnetic impurity and the surrounding spins of the conduction electrons. In Scanning Tunneling Spectroscopy (STS) experiments this effect causes a sharp resonance around zero bias, with a lineshape that depends on the balance between different competing tunneling pathways in the tip/unpaired spin/surface junction. The resonance´s lineshape is described by a lorentzian curve for the case of a preferential tunneling through the unpaired spin, and shows an increasing asymmetry for higher contributions of direct tunneling pathways into the surface. Here we study the variation of the above described lineshape in a charge transfer monolayer formed by Na atoms and TNAP (tetracyanonaphtoquinodimethane) molecules deposited on a Au(111) surface. The electron donated by the Na atoms is localized in the single occupied molecular orbital (SOMO) of the acceptor TNAP [1] and gives rise to the Kondo resonance in STS spectra [2]. We observed intramolecular changes in the shape and intensity of the resonance along the TNAP backbone, with a symmetry change at the nodal planes of the singly occupied molecular state. Through the analysis of these lineshape variations we can locally map the relative weight of the different tunneling pathways existing in the metal-molecular system.

T.R. Umbach, I. Fernandez-Torrente, M. Ruby, F. Schulz, C. Lotze, R. Rurali, M. Persson, J.I. Pascual, K.J. Franke. New Journal of Physics, Vol. 15, page 0830048 (2013)

I. Fernandez-Torrente, K. J. Franke, J. I. Pascual. Physical Review Letters, Vol. 101, page 217203 (2008)

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P3

Mechanical Force Modulates the Unfolding Pathways of the Cold-Shock Protein B from Thermotoga Maritima

Jörg Schönfelder1,2, Raul Perez-Jimenez3, 4, Victor Muñoz1,2,5

1 IMDEA Nanociencia, Faraday 9, Cuidad Universitaria Cantoblanco 28049, Madrid, Spain. Tel: +34 91 299 8878; 2 CNB, Centro Nacional de Biotecnologia, Darwin 3, Cuidad Universitaria Cantoblanco, 28049

Madrid, Spain, Tel: +34 91 585 5422; 3 CIC NanoGUNE, Tolosa Hiribidea, 76, 20018 San Sebastian, Spain, Tel: +34 943 57 4009; 4.IKERBASQUE, Basque Foundation for Science, Bilbao, Spain; 5 University of

Maryland, Department of Chemistry and Biochemistry, College Park, MD, USA

The fundamental concept of reconstructing experimentally the (un)folding energy landscape (FEL) of any protein structure is to study its conformational dynamics and stability in order to track its folding reaction. Over the last decades Single Molecule Force Spectroscopy (SMFS) has become an essential experimental technique allowing investigating protein dynamics through the application of a mechanical force.[1,2] In our work the characterized cold-shock protein B from Thermotoga Maritima (TmCSP) has been found to follow a multi-state unfolding scenario when applying a mechanical force, whereas it folds/unfolds within a conventional 2-state mechanism when using a chemical denaturant using Single Molecule Fluorescence Spectroscopy (FRET).[3] This strongly suggests that mechanical force can be used as a probe to investigate otherwise hidden intermediates in the (un)folding FEL of the TmCSP.

Our approach is to probe the mechanical properties of TmCSP experimentally using the Atomic Force Microscope (AFM) in both the constant velocity and the constant force modes. In these modes the AFM cantilever applies a mechanical force on the single protein either uncontrolled (constant velocity) or controlled by using a PID feedback loop (constant force). The chosen small 66 residue cold shock protein B from Thermotoga maritima consists of 5-beta sheets forming a compact barrel. Additionally it is an ideal candidate to conduct SMFS experiments as it has a small but detectable unfolding force of 70pN[4]. It is also decribed to fold very fast to completion in ms range[5]. In order to conduct the single molecule force spectroscopy experiments we built one polyprotein construct using biomolecular techniques consisting of the TmCSP domain flanked by three Titin I27 domains on each side. Combining experiments with an AFM (PicoForce ,VEECO) working at constant velocity and a Force Clamp AFM (Luigs & Neumann), which operates at constant force, we were able to detect and measure the mechanical unfolding patterns of the individual´TmCSP domain.

First, in our results we could confirm the single-step mechanical unfolding behavior of the TmCSP[4] in constant velocity mode working in the high force regime. However in force ramp and in constant force experiments working in the low force regime 20-80pN with the Force Clamp AFM we were able to detect a high fraction of traces that display complex mechanical unfolding of TmCSP resembling a clear multi-state unfolding behavior. Furthermore we found that there is a certain force regime exsisting at wich the amount of unfolding intermediates is highest. Hence the mechanical unfolding pathway of TmCSP can be modulated by the applied force in the low force regime.

[1]. Nagy et al. Nat Methods. 2008 5(6):491-505.


[2]. M. Schlierf, H. Li, and J. Fernandez. PNAS. 2004, Volume 101, 19, 7299-7304 [3]. B. Schuler, E. Lipman, W. Eaton, Nature. 2002, Volume 419, 743–747 [4]. T. Hoffmann, K.M. Tych, D.J. Brockwell, and L. Dougan, J. Phys. Chem. B 2013, 117, 1819−1826 [5]. F.X.Schmid et al, Nature Struct. Biol. 1998, Volume 5, Number 3, 229-35

P4

Replication Initiation Proteins Studied With Atomic Force Microscopy

Maria Eugenia Fuentes-Perez1, Katarzyna Wegrzyn2, Igor Konieczny2, Fernando

Moreno-Herrero1

1 Department of Macromolecular Structures, Centro Nacional de Biotecnologia, CSIC, Darwin 3, 28049 Cantoblanco, Madrid, Spain. 2 Department of Molecular and Cellular Biology, Intercollegiate Faculty of

Biotechnology, University of Gdansk, Gdansk, Poland.

DNA replication is a fundamental cellular process whose mechanism is still not well understood. Replication requires a specific DNA region, known as the origin of replication (Ori), as well as specific proteins, called replication initiation proteins (Rep). Both DNA and proteins form the replication initiation complex. The origin of replication in plasmids and phage DNA contains some conserved elements. These include specific binding sites (iterons) for Rep proteins, DnaA boxes for DnaA proteins and an AT-rich region where DNA melting occurs. In this work, we used the Atomic Force Microscope (AFM) to study the binding of Rep proteins to the origin of replication in the broad-hostrange plasmid RK2 [1]. The origin of replication in RK2 plasmid is called OriV. It possesses 5 iterons where the replication initiation protein TrfA binds, four DnaA boxes for DnaA proteins and four 13-meres in the AT rich region [2]. Using the AFM, we were able to capture the binding of TrfA to the iterons region. Interestingly, while bound to the iterons, TrfA also interacts with a ssDNA oligonucleotide containing the sequence of one of the strands of the AT rich region. Moreover, the TrfA-ssDNA interaction is dependent on the sequence of the oligonucleotide. Our AFM approach was also applied to RepE protein, a replication initiation protein from plasmid F. Notably, we found that binding of RepE was also favored by the equivalent ssDNA oligonucleotide of the AT-rich region of plasmid F. These findings enable to create a general model in which firstly, Rep proteins induces the melting of the AT-rich region and secondly, specific interaction of Rep protein with one of the melted ssDNA occur.

Doran, K.S., I. Konieczny, and D.R. Helinski, Replication Origin of the Broad Host Range Plasmid RK2. Journal of Biological Chemistry, 1998. 273(14): p. 8447-8453.

Rajewska, M., K. Wegrzyn, and I. Konieczny, AT‐rich region and repeated sequences–the essential elements of replication origins of bacterial replicons. FEMS microbiology reviews, 2011. 36(2): p. 408-434.

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P5

Design an Iterative Learning Observer to Reconstruct the Interaction Force in AM-AFM

F. Payam, D. Martin-Jimenez, R. Garcia


Extracting the time varying tip-sample interaction force in dynamic atomic force microscopy has been an important goal to improve the imaging capabilities of AFM with simultaneous measurements of material properties [1-4]. Here, we design an Iterative Learning Observer to reconstruct the interaction force from the wave profile of the cantilever. In this method, the interaction force is considered as an unknown time varying parameter and estimated by the designed observer.

Simulations and experiments prove the accuracy of this method in liquid and air for different materials. From the reconstructed force signals, we are able to obtain the average peak force, and consequently, using Hu and Raman equation [5], the Young modulus of the materials.

(a) Topography image of Polystyrene (PS) and Polyolefin Elastomer (LDPE) blend. (b) Signal and

reconstructed force of PS (A0=78nm) (c) Signal and reconstructed force of LDPE (A0=78nm). M. Stark, R,W.Stark, W.M. Heckl and R. Guckenberger, PNAS, 99, 13, 8473-8478, (2002). J. Legleiter, M. Park, B. Cusick and T. Kowalewski, PNAS, 103, 13, 4813-4818, (2006). S. Santos, K. Gadelrab, J. Font and M. Chiesa, New Journal of Physics, 15, 083034, (2013). A. Sikora and L. Bednarz, Meas. Sci. Technol., 22, 094005 (2011). S. Hu and A. Raman, Appl. Phys. Lett., 91, 123106, (2007).

P6

STM And Nc-AFM Investigation Of Submonolayer Copper Oxide Structures

Carmen Ocal1, Esther Barrena

1, Sonia Matencio

1

1 Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra, Spain


With the aim of obtaining laterally heterogeneous surfaces with catalytic properties, submonolayer coverages of ultrathin copper oxides on Cu(111) have been grown by air injection and annealing in UHV [1-3] and investigated by means of STM/nc-AFM. Different oxide surface structures have been observed depending on the stoichiometric oxygen/copper ratio, some of which have been already reported [1, 2]. In addition, a new open honeycomb structure with a relatively large unit cell lattice parameter of ~1.3 nm has been observed that nucleates and grows at the step edges of the oxide terraces. This oxide structure can be visualized as an ordered surface network which might serve as nanopattern template for controlled molecular organization (i.e. in a bottom-up approach). Moreover, derived from the expected semiconducting character of the oxide, the ultrathin layer would offer as well an effective electronic decoupling of the organic molecules from the metal surface.

José A. Rodriguez, Journal of Physical Chemistry C 114, 17042-17050 (2010) C. Pérez León, Physical Review B 85, 035434 (2012) F. Wiame, Surface Science 601, 1193-1204 (2007)

P7

Structural Control Of Bridge State Resonances In Single Molecular Junctions

Carly Brooke1, Andrea Vezzoli

1, Simon J. Higgins

1, Linda A. Zotti

2, Juan Jose Palacios

2,

Richard J. Nichols1

1 Department of Chemistry. University of Liverpool. Liverpool. United Kingdom 2 Departamento de Física

de la Materia Condensada. Universidad Autónoma de Madrid. Madrid. Spain

In this contribution, we demonstrate structural control over a transport resonance in HS(CH2)n[1,4–C6H4](CH2)nSH (n = 1, 3, 4, 6) metal | molecule | metal junctions, fabricated and tested using the scanning tunnelling microscopy- (STM-)based I(s) method. Varying the number of methylene groups controls a transport resonance associated with the central arene moiety, in turn leading to a very shallow decay of the conductance with the length of the molecule. Quantum mechanical control of this phenomenon comes from a Breit-Wigner resonance in the transmission curves of HS(CH2)n[1,4–C6H4](CH2)nSH which sharpens and moves closer to the contact Fermi energy as n increases. Such resonances offer future prospects in molecular electronics in terms of controlling charge transport over longer distances, and also in single molecule conductance switching if the resonances can be externally gated. We further demonstrate that the electrical behaviour observed here can be straightforwardly rationalized, using the ideas of semiconductor physics, in terms of a pair of back-to-back Schottky diodes.

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P8

Magnetic Force Microscopy Of Focused Ion Beam Patterned Co Antidot Arrays

Andreas Kaidatzis1,3

, Rafael Pérez del Real2, Raquel Alvaro

3, Jose V. Anguita

3, Manuel

Vazquez2, José Miguel García-Martín

3

1 Institute of Nanoscience and Nanotechnology, NCSR “Demokritos”, Athens, Greece 2 ICMM-Instituto

de Ciencia de Materiales de Madrid, CSIC, Madrid, Spain 3 IMM-Instituto de Microelectrónica de Madrid, CSIC, Tres Cantos, Madrid, Spain

Continuous magnetic films with patterned groups of ordered holes, known as magnetic antidot arrays, are being intensively investigated as candidates for high-density storage media [1] and as magnonic crystals for magnetic logic applications [2]. The main parameters that influence the magnetic properties of the array are its symmetry and lattice constant and the shape and size of the antidots. The main focus of antidot arrays studies has been on square or hexagonal symmetry arrays of circular antidots, on the μm- and sub-μm-scale, fabricated by patterning methods like UV [3] or e-beam [4] lithography. On the other hand, nm-scale antidot arrays can be attained by various self-assembly techniques employing, e. g., porous anodic alumina [5] or colloidal lithography [6]. However, there are significant inherent drawbacks in all of the self-assembly fabrication methods, mainly regarding the limitations in the array symmetry and/or size and the extent of the symmetric domains, which is on the order of some μm

In this work, nm-scale antidot arrays have been fabricated using focused ion beam nanopatterning and characterized by magneto-optical Kerr effect magnetometry and atomic/magnetic force microscopy. Continuous Ti (2 nm)| Co(10 nm) | Au(10 nm) stacks were evaporated in an ultra-high vacuum chamber on monocrystalline (0001) sapphire substrate. The substrate was rotated around its normal during the deposition in order to avoid the formation of strong magnetic anisotropy during the growth of the film. The antidot arrays


were directly etched on the continuous stack using an IonLine FIB machine, with Ar ions at energy of 30 keV and ion current of 6.9 pA. Square and hexagonal symmetry arrays have been studied with lattice constant ranging from 150 nm to 300 nm and antidot diameter 55 nm, see Fig. 1. We find an intense increase of the magnetic coercivity (Hc) of the film after patterning, with a monotonic increase of Hc as the density of defects increases. Additionally, the in-plane anisotropy axes of the patterned film depend strongly on the array symmetry, with alternating hard and easy axes following the array symmetry. High resolution MFM images reveal the magnetic structure of the arrays. In clear contrast to the unpatterned film, where abrupt contrast changes correspond to domain wall dragging under the influence of the magnetic stray field of the MFM tip (Fig. 2a), the antidot arrays exhibit stable magnetic domains whose inner structure is commensurate to the array symmetry (Fig. 2b-2d). It is concluded that nanopatterned anti-dot arrays provide an effective means to engineer the magnetic properties of thin films.

Figure 1. Atomic force microscopy images revealing (a) the global morphology of a representative antidot array and (b) the two array symmetries studied and the antidot shape and size.

Figure 2. MFM images of (a) unpatterned Co film, (b) hexagonal antidot array demagnetized along 0o, (c) square antidot array demagnetized along 45o, and (d) square antidot array demagnetized along 30o

C. Wang et al., Nanotechnology 17, 1629 (2006) R. Bali et al., Phys. Rev. B 85, 104414 (2012) L. J. Heyderman et al. Phys. Rev. B 73, 214429 (2006). P. Vavassori et al. Phys. Rev. B 59, 6337 (1999). D. Navas et al. Appl. Phys. Lett. 90, 192501 (2007). M. E. Kiziroglou et al. J. Appl. Phys. 100, 113720 (2006). Acknowledgments Funding from CSIC (i-LINK0783), MINECO (MAT2011-29194-C02-01, MAT201020798-C05-

01 and CSD2008-00023) and EU (PIEF-GA-2010-272470) is acknowledged.

P9

Investigating Subsurface Boron Dopants In Si(111)-(√3x√3) R30° Using Simultaneous Nc-AFM/STM And DFT

Jan Berger1,2, Evan J. Spadafora1, Pingo Mutombo1, Mykola Telychko1, Martin

Ondráček1, Martin Švec

1, Alastair McLean

3, Pavel Jelínek

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1 Institute of Physics, Academy of Sciences of the Czech Republic, Prague, Czech Republic 2 CTU Prague, Faculty of Nuclear Sciences and Physical Engineering, Czech Republic 3 Department of Physics, Queens

University, Kingston, Ontario, Canada

B:Si(111)-(√3x√3)R30° surface has gained a lot of interest in surface science, due to its prominent electronic and structural properties. Compared to bare silicon surface, this system has reduced chemical reactivity, which makes it a suitable candidate for deposition of molecular complexes without a risk of their decomposition. Here, we investigated the near surface defects of this delta-doped system using a combination of scanning tunneling microscopy, non-contact atomic force microscopy, ab initio and Green function theoretical methods. We make positive assignments of two near surface defects: the adatom vacancy and a B substitutional defect that is located in the second Si bilayer. We also confirm the previously reported assignment of the dangling-bond defect. Additionally, the influence of the subsurface defects on the surface electronic structure, in particular the modulation of the surface potential, is investigated using Kelvin probe force microscopy, scanning tunneling spectroscopy and large scale density functional theory calculations. The effects of solitary dopants can play a significant role on commercial device performances as well as on the fundamental local properties of a semiconductor. Therefore, this study paves the way for a deeper understanding of passivated Si surfaces used for the development of molecular thin films and devices.

P10

Probing The Fermi Surfaces Of The Two-band Superconductor Lead

B. W. Heinrich1, M. Ruby

1, J. I. Pascual

2, K. J. Franke

1

1 Institut für Experimentalphysik, Freie Universität Berlin, Germany 2 CIC NanoGUNE and Ikerbasque, Donostia-San Sebastian, Spain

Recent density functional theory simulations have shown that the two separated Fermi-surfaces of the strong-coupling s-wave BCS superconductor lead (Pb) exhibit different character in momentum space, namely s-p- and p-d-like [1]. The two Fermi-surfaces make Pb a two-band superconductor with a different gap parameter for each band. We use scanning tunneling microscopy and spectroscopy at 1.2 K to experimentally probe the two-band superconductivity of lead on low-index surfaces of Pb single crystals. In the excitation spectrum, we observe for all surfaces two quasi-particle resonances at each side of the gap, which appear due to the two gap parameters. They have an energy difference of 150 µV and differ remarkably in intensity. We then use dI/dV mapping around subsurface defects to characterize the two Fermi surfaces in real space -similar to the Fermi surface mapping of a one-band conductor in Ref. 2. Furthermore, we study the influence of lead adatoms on the tunneling spectra, unveiling different localization characteristics for the two bands.


A. Floris et al., Phys. Rev. B 75, 054508 (2007). A. Weismann et al., Science 323, 1190 (2009).

P11

Boron- and Nitrogen-doped Multiwall Carbon Nanotubes Studied By Kelvin Probe Microscopy

J. F. González-Martínez 1, J. Abad2, J.-S. Park3, J.-M. Lee3,4, S.-O. Kim3,4, J.-S. Kim3,5, A. Urbina5,2 and J. Colchero1

1 Department of Physics, University of Murcia, Campus Espinardo, 30100 Murcia, Spain; 2 Departments of Applied Physics and Electronics, Technical University of Cartagena, Plaza Hospital 1,30202 Cartagena,

Spain; 3 Department of Materials Science and Engineering, Korea Advanced Instituteof Science and Technology (KAIST), 305-701, Daejeon, Republic of Korea; 4 Center for Nanomaterials and Chemical

Reactions, Institute for BasicScience (IBS), Daejeon 305-701, Republic of Korea; 5 Department of Physics and Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, UK

Carbon nanotubes have been thoroughly studied in the past twenty five years because of their exceptional physics properties. However, in recent years a great interest has been observed towards improving and controlling their properties through different functionalization methods. The modification of the nanotube properties by controllably placing defects or heteroatoms can lead to huge technological implications [1]. The introduction of hetero-atoms such as Nitrogen or Boron into Carbon Nanotubes offers the possibility of tailoring their structural and electronic properties [2]. In particular, substitution of Boron or Nitrogen in Carbon nanostructures can render them p-type or n-type, respectively. Nitrogen-doped multi-walled Carbon Nanotubes (MWNTs) exhibit interesting electrical transport properties, as a higher conductance than undoped ones [3]. Besides, nitrogen-doped MWNTs exhibit excellent electron emission behaviour [4]. While for boron-doped MWNTs a metallic character and an enhanced resistance towards oxidation have been reported. In this work we have investigated undoped, and boron- and nitrogen-doped MWNTs which have been previously used to fabricate organic solar cells [5] and characterized by Raman spectroscopy [6]. The experiments presented in this communication have been performed by means of Electrostatic Force Microscopy (ESF), Kelvin Force Microscopy (KPM) and 3D modes including force spectroscopy,

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in ambient and vacuum conditions. Bundles and individual multiwall nanotubes have been studied on a graphite substrate, allowing us to obtain the work function by direct measurement using the substrate graphite signal for proper calibration and therefore identifying the p-type and n-type character of the doped nanotubes. The understanding of doping effects on the electronic performance of devices based on carbon nanotubes is a crucial point for the development of nanotube-based nanoelectronics and to the discovery of new functionalities.

M. Dresselhaus, G. Dresselhaus, P. Avouris. Carbon nanotubes: synthesis, structure, properties, and applications. ( Springer-Verlag, Germany, 2001)

O. Stéphan, P.M. Ajayan, C. Colliex, P. Redlich, J.M. Lambert, P. Bernier, P. Lefin, Science 266, 1683 (1994) R. Sen, et al, Chem. Phys. Lett. 287, 671 (1998) M. Doytcheva et al. , Chem. Phys. Lett. 396, 126 (2004) J. M. Lee, J. S. Park, S. H. Lee, H. Kim, S. Yoo and S. O. Kim, Adv. Mater. 23, 629 (2011) A. Urbina, J. S. Park, J. M. Lee, S. O. Kim and J.-S. Kim, Nanotechnology 24, 484013 8 (2013)

P12

Calibration of Normal Force using non-destructive Dynamic Force Microscopy

Juan Francisco González Martínez1, Jaime Colchero Paetz1 1Instituto Universitario de Investigación en Óptica y Nanofísica, Campus de Espinardo, Universidad de

Murcia, E-3100, Spain

A method to precisely calibrate the normal force based on Dynamic Scanning Force Microscopy techniques is described. Many methods have been proposed to calibrate the deflection of the cantilever [1- 3]. We recall here two of them: the first one based on measurement of the slope of a force distance curve while the second one is based on the equipartition theorem,

kB T /2= c zth2/2 (1)

(kB, the Boltzmann constant; T, temperature; c, the force constant of the cantilever and zth, the displacement of the free end of the cantilever). We recall relation (1) has two unknowns, the force constant c and the sensitivity β of the detection system that converts the signal in volts, u(t) into nanometers: z(t)= β u(t). If the force constant c is known (for example, using Sader’s method [4]), then the thermal noise relation (1) can be used to determine the sensitivity β, that is, the calibration of the normal force.

In the present work we will describe how to calculate the sensitivity using Dynamic Force Microscopy techniques. Essentially, we adapt a method to calibrate the oscillation amplitude [5] based on thermal noise, and will show that the results agree well with the classical determination of sensitivity as calculated from force vs. distance curves. The method proposed in this work uses the thermal noise through the electronics used to process the signals in Dynamic Force Microscopy. This methods has the following advantages,

1. It is possible to calibrate the normal force and the oscillation amplitude [5] simultaneously.


2. A better signal to noise ratio is obtained due to Dynamic Electronics and the lower bandwidth of electronics.

3. The method is “non-contact”, therefore even for very sharp tips their integrity is preserved.

Experimentally the method proposed works up to cantilevers with c<70 N/m, otherwise there are still unsolved difficulties.

R. S. Gates et al., J. Res. Natl. Inst. Stand. Technol. 116, 703–27 (2011). J. te Riet et al., Ultramicroscopy 111, 1659–69 (2011). N. A. Burnham et al., Nanotechnology 14, 1–6 (2003). J. E. Sader, J.W.M. Chon and P. Mulvaney, Rev. of Scien. Inst. 70, 3967-9 (1999). J. F. González Martínez, I. Nieto-Carvajal, J. Colchero, Nanotechnology 24, 185701 (2013).

P13

Modelling dissipation in Dynamic Scanning Force Microscopy as a function of tip-sample distance

Juan Francisco González Martínez1, Jaime Colchero Paetz1 1Instituto Universitario de Investigación en Óptica y Nanofísica, Campus de Espinardo, Universidad de

Murcia, E-3100, Spain

The quality factor is a key parameter for Dynamic Force Microscopy, since it determines a series of important properties of the system, such as the energy stored in the system, the width of the resonance curve, the resonance enhancement, but also the response to non-linear interactions, and the response of a Phase-Locked Loop in the so called Frequency Modulation mode. For operation in non-vacuum environment –that is in air or liquids, the quality factor is essentially determined by the surrounding viscous medium. In the present work the behaviour of a Scanning Force Microscopy (SFM) cantilever in viscous media is studied, with particular emphasis on how the viscosity of these media reduces the quality factor. A simple theoretical model is proposed based on the assumption of a composed probe model:

SFM probe = microscopic cantilever + mesoscopic tip cone + nanometric tip apex

This model correctly describes the dissipation for a variety of cantilevers in different media (fig. 1). It is shown that the physical dimensions of the cantilever as well as the viscosity of the medium where it is immersed determine the dependence of the quality factor with the cantilever-sample distance. For the range of distances explored in this work, it is shown that the Reynolds number is a key parameter to select a cantilever in a specific medium, in order to achieve the highest quality factor at small cantilever-sample range.

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Figure 1: This graph shows the dependence of the quality factor with distance for different media (air, water, ethanol, toluene and acetone). Note that for better visibility the curve in air has been divided by 10. The Reynolds number (Re) for each case has also been added. In this particular case, a silicon nitride cantilever (length, 100 microns; width, 20 microns; elastic constant, 0.04 N/m) has been used.

P14

Structure–performance Relationships In Solution-processed Organic Solar Cells Based On Acceptor-substituted S,N

Heteroacenes

Marta Urdanpilleta1,2

, Hannelore Kast1, Amaresh Mishra

1, Gisela L. Schulz

1, Elena

Mena-Osteritz1, Peter Baeuerle1

1 Institute of Organic Chemistry II and Advanced Materials, University of Ulm, AlbertEinstein-Allee 11 D-89081 Ulm, Germany 2 Dpto. Física Aplicada I, Universidad del País Vasco (UPV/EHU),Pl. Europa 1, 20018

Donostia, Spain

The application of organic materials for the photovoltaic conversion corresponds to the third generation of solar cells. These systems are gaining ground to the classical siliconbased ones, due to their mechanical flexibility, low weight, low cost and eco-friendly potential.

The synthesis of oligomers is emerging as a viable strategy to expand the structural diversity relevant to organic electronic applications. The advantage of the oligomeric (or small molecule) approach is that they are defined, monodispersed molecules able to crystallize: the structure-properties relationship of the photovoltaic devices employing oligothiophenes can be thus univocally established.

The solar cell devices based on small molecules are recently attracting increasing attention because of their advantages above conjugated polymeric systems in terms of easiness of purification, higher homogeneity between batches, and therefore higher reproducibility concerning efficiency of the devices. Power conversion efficiencies (PCE) up to 6.9% have been reported for oligomers based on vacuum-processed [1] and 9% for solutionprocessed single junction devices [2,3]. For this type of devices, probe microscopy can give insights into the morphological distribution of the donor and acceptor within the blend of the photoactive layer, a crucial parameter for the cell performance. Nanometersize phase separated domains


are necessary to accomplish the needs of exciton diffusion, charge separation and charge carrier transport in the organic photoactive film.

Fused oligomers such as acenes and heteroacenes have attracted growing attention not only with respect to the design of new materials but also for their applications in organic field effect transistors (OFET) and organic solar cells (OSC). As an example, pentacene have shown high

hole mobility of up to 5 cm2 V

-1s

-1 in bulk and up to 40 cm

2 V

-1s

-1 in single crystal [4].

In this contribution, the surface properties of solar cell devices based on acceptorsubstituted fused heteroacenes as a donor material have been studied with atomic force microscopy (AFM), and results correlating the solar cell performance and the surface characteristics will be discussed.

R. Fitzner, E. Mena-Osteritz, A. Mishra, G. Schulz, E. Reinold, M. Weil, C. Körner, Ziehlke, C. Elschner, K. Leo, M. Riede, M. Pfeiffer, C. Uhrich and P. Bäuerle, J. Am. Chem. Soc., 134 (2012) 11064

J. Zhou, X. Wan, Y. Liu, Y. Zuo, Z. Li, G. He, G. Long, W. Ni, C. Li, X. Su and Y. Chen, J. Amer. Chem. Soc., 134 (2012) 16345

V. Gupta, A. K. K. Kyaw, D. H. Wang, S. Chand, G. C. Bazan, A. J. Heeger, Sci. Rep. 3 (2013) 1965 J. Mei, Y. Diao, A. L. Appleton, L. Fang, Z. Bao, J. Am. Chem .Soc. 135 (2013) 6724

P15

Ether Groups And Acyl-chain Branching Reduce Nanomechanical Resistance Of Phospholipid Bilayers: A Force

Spectroscopy Study

Aritz B. García-Arribas1,2

, Jesús Sot1,2

, Daniel Balleza1,2

, Kepa Ruiz-Mirazo1,3

, Alicia

Alonso1,2

, Félix M. Goñi1,2

1 Unidad de Biofísica (Centro Mixto CSIC, UPV/EHU), Leioa, Spain. 2 Departamento de Bioquímica, Universidad del País Vasco (UPV/EHU), Leioa, Spain. 3 Departamento de Lógica y Filosofía de la Ciencia,

UPV/EHU, Av. Tolosa 70, 20018 Donostia-San Sebastián, Spain.

Atomic force microscopy (AFM) has been applied to the characterization of nanomechanical resistance of lipid bilayers to study the effect of ether-linking and acylchain branching. For this purpose, supported planar bilayers (SPBs) were obtained from small unilamellar vesicles (SUVs) of pure lipids by the vesicle adsorption method onto mica substrates and analysed by force spectroscopy at 23 ºC. Lipids studied were dipalmitoyl phosphatidylcholine (DPPC, ester group, nonbranched acyl-chain), dihexadecyl phosphatidylcholine (DHPC, ether, nonbranched), diphytanyl phosphatidylcholine (DPhPC, ether, branched) and diphytanoyl phosphatidylcholine (DPhoPC, ester, nonbranched). The presence of ether groups and acyl-chain branching both enhance fluidity: nonbranched lipids (DPPC, DHPC) form lamellar gel phases at 23 ºC, whereas branched lipids (DPhPC, DPhoPC) form lamellar fluid phases, with lower breakthrough forces. DPhPC, both ether-linked and branched, yields the lowest breakthrough force values. DPhoPC exhibits higher breakthrough force values than typically expected in a fluid phase. Special properties of this lipid have been reported: e.g. abnormally low water permeabilization when compared to other fluid-phased phosphatidylcholines such as POPC or DOPC [1]. In the case of

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DHPC, SPB imaging reveals transient coexistence of two different lamellar gel-phases at 23 ºC, due to the lack of equilibrium, and a suggested metastable interdigitated gel phase is observed [2], with reduced thickness and higher breakthrough force. Ether-linked and acyl-branched (isoprenoid) lipids are common in Archaea (as sn-glycerol-1-phosphate isomers) and this study becomes relevant in the context of the “lipid-divide” hypothesis and the development of early membranes of the evolutionary precursors of cells.

[1]. S. Tristram-Nagle, D.J. Kim, N. Akhunzada, N. Kučerka, J.C. Mathai, J. Katsaras, M. Zeidel, and J.F. Nagle. Chem. Phys. Lipids. 163:630–637 (2010).

[2]. S.D. Guler, D.D. Ghosh, J. Pan, J.C. Mathai, M.L. Zeidel, J.F. Nagle and S. Tristram-Nagle. Chem. Phys. Lipids. 160:33-44 (2009).

P16

Understanding Transverse Shear Microscopy In Crystalline Organic Layers

A. Pérez-Rodríguez1, A. Fernández

2, C. Ocal

1, E. Barrena

1

1 Institut de Ciéncia de Materials de Barcelona, Campus de la UAB, 08193, Bellaterra, Spain 2 Graz University of Technology,8010 Graz, Austria

Over the past two decades conventional lateral force microscopy (LFM) also known as friction force microscopy (FFM), has become the primary tribological technique for examining surfaces frictional response at nanometer scale. LFM detects the cantilever torsion resulting from frictional forces between tip and surface by setting the fast-scan direction orthogonal to the cantilever axis. However, the torsion signal may also be collected by setting the fast-scan direction parallel to the cantilever axis. Recently, this imaging mode has been referred to as transverse shear microscopy (TSM) [1]. The TSM signal provides a rich map of contrasts in molecular crystals that has successfully been employed for revealing the azimuthal orientation of crystalline domains in crystals and thin films of pentacene [1,3] and hydrogen phthalate[3]. The relation between the TSM signal and the crystallographic directions of the molecular surface has been demonstrated.

However, the quantitative interpretation of the rather surprising TSM contrast in organic materials is controversial [2,3]. Here we perform a TSM and LFM study of N,N′-dioctyl-3,4:9,10-perylene tetracarboxylicdiimide (PTCDI-C8 ) with the goal of gaining understanding on the origin of TSM in molecular surfaces. Unlike the two previously investigated molecules, PTCDI-C8 does not order in a herringbone structure but in rows of co-facially stacked molecules with a tilt of ~35-40° respect to the vertical. For this study two-dimensional crystalline islands of PTCDI-C8 have been grown on silicon dioxide at submonolayer coverage. We have performed molecular-resolution images in different domains and compared the TSM and LFM response in relation to the orientation of the resolved lattice. The stick-slip motion in TSM and LFM and its dependence with the applied load have also been studied.


V. Kalihari et al. Adv. Mat. (2008), 20, 4033 M. Campione et al. PRL 105, 166103 (2010) V. Kalihari et al. PRL 104, 086102 (2010

P17

α-Fe2O3(0001) Surface As A Model Catalyst: Morphology And Electronic Structure

Sara Barja1,2

, Alexander Weber-Bargioni2, Miquel Salmerón

1,2,3

1 Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States. 2 Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, United States. 3 Department

of Materials Science and Engineering, University of California Berkeley, Berkeley, CA, United States

Semiconductor based photo-catalysts have been studied for many years as a potential solution for clean, large-scale hydrogen fuel production, as well as to degrade pollutants in contaminated water. However, the efficiency of these processes is still too low to be practical. Fundamental understanding of the correlation between catalyst’s morphology, energy level alignment between catalyst and reactant and the local photo catalytic activity is crucial for a systematic optimization of the mechanisms behind photo catalytic reactions, a key to enhance the impact of green chemistry 1. Here, we present our first results correlating surface morphology, surface electronic structure and local distribution of photo excited carriers with atomic resolution in the α-Fe2O3(0001) model catalyst. Our tool is Low Temperature Scanning Tunneling Microscopy/Spectroscopy in Ultra High Vacuum with and without band gap illumination (480 nm). α-Fe2O3(0001) single crystal – hematite phase- exhibits fundamental properties ideal as a model system for solar catalytic process: it is an n-type semiconductor with a band gap of approximately 2.2 eV, earthabundant, relatively easy to synthesize, cheap and environmental benign. In addition, depending on the different conditions of temperature and oxygen partial pressure during αFe2O3(0001) single crystal preparation under Ultra High Vacuum conditions, a mixture of Fe2O3 (0001), Fe3O4 (111) and FeO (111) surfaces is commonly observed 2,3. In particular, in this work we show how the local electronic structure of the Fe3O4 (111) surface domain is modified due to the presence of different point-defects

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(Fe- or Ovacancies and Fe- adatoms) that have each a unique signature in the tunneling spectra. We found that under illumination the distribution of photo excited carriers is governed by the local surface potential variations. Hence, by comparing the electronic structure under illumination to the one obtained in the dark, we can determine the distribution of optically excited charge carriers that will drive the photochemical reaction. Our ultimate goal is to understand and eventually predict how the morphology, optically excited electronic structure and local photo catalytic rate are correlated for a systematic development of novel artificial photo catalytic systems.

[1]. Walter, M. G. et al. Chemical Reviews 110, 6446–6473 (2010). [2]. Condon, N. G. et al.). Surface Science 397, 278–287 (1998). [3]. Tang, Y., Qin, H., Wu, K., Guo, Q. & Guo, J.. Surface Science 609, 67–72 (2013). [4]. Yin, S. & Ellis, D. E.. Surface Science 602, 2047–2054 (2008).

P18

Surface Charge Differentiation of Avidin and Streptavidin By AFM-Force Spectroscopy

L. Almonte, E. López-Elvira, A.M. Baró

Instituto de Ciencia de Materiales de Madrid-CSIC, Madrid, Spain

Chemical analysis of matter consists of the determination of either elemental or molecular composition. The amount of material required for chemical analysis has decreased continuously as increasingly sensitive analysis tools have become available. Atomic force microscopy (AFM) is a powerful technique for studies of biological samples due to its ability to measure forces in real time and in liquid media with atomic or molecular resolution [1]. In addition chemical information can be obtained by Force Spectroscopy (FS), which is based on the measurement of force vs. distance curves F(d) in the pN range.

In this it work has been possible to distinguish between single molecules of avidin and streptavidin anchored to a biotinylated bilayer even though AFM topographic images of both proteins cannot be distinguished, because their protein structures are almost identical. This differentiation can be achieved due to the different surface charge of both proteins. Indeed, avidin is a basic glycoprotein, pI = 10.5, so that avidin is positively charged [2] whereas streptavidin is non-glycosylated with a near-neutral pI at pH=7. This charge difference has been determined by AFM which can probe electrostatic double layer (EDL) forces by FS. The F(d) curves due to the electrostatic interaction have significant differences when measured on top of each molecule of streptavidin and avidin (figure 1(a)) as well as on the lipid substrate where they are fixed. Figure 1(b) shows the normalized force values to tip radius obtained for both proteins as well as for supported lipid bilayer (SLB). Moreover, FS data show that the two proteins are negatively charged since the curves are repulsive. Notwithstanding avidin and streptavidin can be clearly distinguished, which shows the sensitivity of AFM to detect the charge state of macromolecules.


J. Sotres, A.M. Baró, Biophys. J. 98, 1995-2004 (2010) M.D Savage, G. Mattson, S. Desai, G.M. Nielander, S. Morgensen, E.J. Conklin, Avidin-Biotin Chemistry: A

Handbook, 2nd ed. (Pierce, Rockford. 1994)

P19

Amplitude modulation dynamic force microscopy for stable imaging of samples with heterogeneus in liquids

Lisa Almonte1, Arturo M. Baró1, Jaime Colchero2 1Instituto de Ciencia de Materiales de Madrid-CSIC, Campus de Cantoblanco E-28049 Madrid

2 Dep. Física. CIOyN. Universidad de Murcia, Campus Espinardo, E-30100 Murcia

Scanning Force Microscopy (SFM) is a powerful tool in the field of Biology and Biophysics due to its ability to image and measure forces of in-vivo biological samples in physiological environment. Biological samples in liquid medium have a surface charge that may be repulsive or attractive depending on local charge of the sample in the medium at a specified pH. To modify or damage the sample as little as possible is important to measure in the non-contact regime. For samples with different local charge domains (“heterogeneous-charge” samples) the acquisition of electrostatic measurements cannot be performed in jumping or frequency modulation (FM-DSFM) in the non-contact regime, because the feedback loop needs a well-defined slope of the interaction curve (normal force and frequency shift). On different charge domain this slope is different (attractive or repulsive) leading to unstable imaging (Fig. 1). The dissipation however, the other DSFM channel related to amplitude, is monotonous. Amplitude modulation (AM-DSFM) is therefore the only technique for stable SFM-images of “heterogeneous-charge” samples.

In this work a lipid bilayer (DOTAP) on mica has been measured in milli-Q water. Frequency shift, phase and amplitude channels are acquired simultaneously with normal force as an additional information channel. Amplitude modulation and frequency modulation have been compared at low oscillation amplitude in dynamic modes: at constant amplitude good topography has is obtained with the correct height (6 nm). This mode is reproducible and non-destructive since low forces are applied. At constant frequency wrong height (3.5nm) has been obtained. In addition, high forces are applied so this mode is destructive if the measurement is instable.

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Fig 1. Attractive and repulsive regime in force-distance curves.

[1] C. Gotsmann, et al., the American Physical Society, 11051 (1999) [2] Johnson A.S. et al., Langmuir 19:10007 (2003)

P20

Detecting charging effects in single molecules by nc-AFM

Fabian Schulz1,2, Christian Lotze1, Martina Corso1,3,4, Isabel Fernandez-Torrente1, Katharina J. Franke1, J. Ignacio Pascual1,3,5

1Freie Universität, Berlin, 14195, Germany; 2Aalto University School of Science, Espoo, 01250, Finland 3IKERBASQUE, 48011, Bilbao, Spain; 4Material Physics Center, 20018, San Sebastián, Spain; 5CIC

nanoGUNE, 20018, San Sebastián, Spain

The ultimate goal in electronic devices miniaturization is the creation of circuit elements (as wires, transistors, rectifiers…) consisting on single molecules. A single molecule transistor exploits the electrostatic modulation of a molecule’s orbital energy. To realize such device a high degree of charge localization is needed in order to allow for discrete changes in transconductance of the molecular device [1]. Charge localization requires minimal hybridization between the molecular orbitals and the states of the leads, and the possibility to tune the charge state of the molecule. Scanning probe techniques offer the unique possibility of addressing such issues in studying single molecules with atomic precision. Scanning tunneling microscopy (STM) has proven its potential to discriminate and manipulate the charge state of single atoms and molecules [2]. Non-contact atomic force microscopy (nc-AFM) allowed as well determining the charge state of those systems [3]. Nevertheless the dynamic response of the AFM to (dis)charging events has been investigated so far for many electron systems as semiconducting quantum dots [4] or nanoparticles [5].

Here we demonstrate the capability of nc-AFM to achieve single-electron sensitivity in processes occurring in single molecules.

The electron acceptor molecule TCNQ embedded into a charge transfer compound (TCNQ-TMTTF) could be (dis)charged by integers of e through gating with the electric field between an STM tip and the Au(111) supporting surface [6]. The critical field inducing the molecular (dis)charging could be tuned with the sample bias voltage or the tip-molecule distance. The latter changes periodically at an oscillating AFM tip. The coupling of the (dis)charging process resonantly with the periodic motion of the AFM tip, results on a change of the measured

Tip-Sample Distance (nm)

Nor

mal

For

ce (p

N)

Repulsive Force

Attractive Force

Tip-Sample Distance (nm)

Nor

mal

For

ce (p

N)

Repulsive Force

Attractive Force


frequency shift (∆f) due to different electrostatic forces in the junction. By sweeping the applied sample bias, ∆f exhibits a pronounced deep whenever the molecule changes from a charged to a neutral state.

[1]. W. Liang, M. P. Shores, M. Bockrath, J. R. Long, H. Park, Nature 417, 725 (2002). [2]. J. Repp, G. Meyer, F. E. Olsson, M. Persson, Science 305, 493 (2004). [3]. L. Gross, F. Mohn, P. Liljeroth, J. Repp, F. J. Giessibl, G. Meyer, Science 324, 1428 (2009). [4]. L. Cockins, Y. Miyahara, S. D. Bennet, A. A. Clerk, S. Studenikin, P. Poole, A. Sachrajda, P. Grutter, PNAS

107, 9496 (2010). [5]. A. Tekiel, Y. Miyahara, J. M. Topple, P. Grutter, ACSNano 7, 4683 (2013). [6]. I. Fernández-Torrente, D. Kreikemeyer-Lorenzo, A. Strózecka, K. J. Franke, J. I. Pascual, Phys. Rev. Lett. 108,

036801 (2012).

P21

Two Dimensional Gadolinium Alloys On Noble Metal Surfaces

Alexander Correa1,2, Bin Xu3,4,5, Matthieu Verstraete3,4, Lucia Vitali2,6

1 Donostia International Physics Center, 20018 San Sebastian (Spain) 2 Departamento de física de materiales, Universidad del País Vasco, 20018 San Sebastian (Spain) 3 Départment de Physique,

Université de Liège, Allée du 6 Août 17, B-4000 Sart Tilman, Belgium 4 European Theoretical Spectroscopy Facility (http://www.etsf.eu) 5 Department of Physics and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, Arkansas 72701 6 Ikerbasque Foundation for Science,

48011 Bilbao (Spain)

The reported fast magnetization switch of thin layers of transition and rare-earth metals or of their alloys has raised the scientific and technological interest due to their potential application in spintronics and data storage [1, 2]. The physical principles behind these observations have not yet been completely clarified: it has been ascribed to the interaction of light with the electron and spin structure of these systems, while an important role in their relaxation and coherent magnetic ordering is due to lattice phonons. Given the potentiality of these observations, it is important to synthesize and characterize these ferromagnetic materials in different chemical compositions such as in alloys with nonmagnetic materials. This creates a new crystallographic, electronic and magnetic structure and can result in a modified exchange mechanism for the magnetic ordering. In this work, we address the structural, electronic and spin characterization of two novel surface alloys based on gadolinium and noble metal surfaces, as Au(111) and Ag(111). These form stoichiometric alloys GdAu2 and GdAg2 with one single Gd atom per unit cell [3,4,5]. These alloys are therefore diluted rare-earth structures, which exhibit a Curie temperature lowered to only ~30K and an in-plane magneto-crystalline anisotropy [4,5]. The incommensurability of the lattice constants of the supporting substrate and of the formed single-layer alloys gives rise to a Moiré structure, where the atoms of the overlayer are in different registry with the substrate. Topographic and local spectroscopic characterization of the density of state of these two superstructures have been achieved at various positions of the Moiré pattern with a scanning tunneling microscope operated at 1 Kelvin. Density functional theory calculations with noncollinear spins have been performed to deepen our understanding of the similarity and peculiarity of these surface alloys in the local density of states as well as in their magnetic properties.

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[1]. C.Stamm et al, Nature Materials 7,740 (2007) [2]. I.Radu et al., Nature 472,205 (2011) [3]. M. Corso, M. J. Verstraete, F. Schiller, M. Ormaza, L. Fernández, T. Greber, M. Torrent, A. Rubio, and J. E.

Ortega, et al. Physical Review Letters 105, 016101 (2010) [4]. L.Fernandez, M.Blanco Rey, M.Llyn, L. Vitali, A.Magaña, A.Correa, P.Ohresser, J.E.Ortega, A.Ayuela,

F.Schiller, submitted for publication [5]. A. Cavalin, L. Fernandez, M. Ilyn, A. Magaña, M. Ormaza, M. Matena, L. Vitali, J. E. Ortega, C. Grazioli, P.

Ohresser, S. Rusponi, H. Brune, F. Schiller, submitted for publication

P22

Elastic-Plastic Switch Of Tomato Bushy Stunt Virus Particles

A. Llauró1, E. Coppari2, F. Imperatori3, A.R. Bizzarri2, L. Santi3, S. Cannistraro2, P. J. de

Pablo1

1 Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, 28049. Madrid, Spain 2 Biophysics and Nanoscience Centre, CNISM-DEB, Università della Tuscia, 01100. Viterbo, Italy 3

Department of Agriculture, Forests, Nature and Energy (DAFNE), Università della Tuscia, Via San Camillo de Lellis snc, 01100 Viterbo, Italy

The study of virus protein shells mechanics in the elastic regime has provided insights into the virus strength and structure, such as the rigidity of the shells or the precursors of the disassembly. However, there is a lack of information about the plasticity of viral cages, including their molecular and structural determinants, which results in the permanent deformation of the viral particles without breakage under mechanical load. Here we investigate the effects of pH and ions sequestration on the mechanics of individual Tomato Bushy Stunt Virus nanoparticles (TBSV-NPs) by using Atomic Force Microscopy (AFM). Our experiments demonstrate that the depletion of calcium ions from the intracapsid binding sites reduces the stiffness of TBSV-NPs and induces an elastic-plastic transition on the mechanical response of these protein shells. Interestingly, we find that this plastic transition is also triggered by mechanical deformation. These findings are further supported by a careful analysis of the virus adsorption geometries on the surface. The structural role of calcium ions establish an inextricable linkage between the molecular and physical determinants of plasticity in TBSV-NPs. We suggest that the ability of TBSV-NPs of being permanent deformed without fracture might not only have implications during the infection of plant cells but also may increase the stability of these cages for cargo transportation at the nanoscale.

P23

Studying The Mechanical Behavior Of Cardiac Stem Cells By Means Of Atomic Force Microscope

R. Daza1,2

, N. Marí1,2

, G. R. Plaza1,2

, B. G. Gálvez3, A. Bernal

3, G. V. Guinea

1,2, J. Pérez-

Rigueiro1,2

, M. Elices1,2


1 Departamento de Ciencia de Materiales. Universidad Politécnica de Madrid. Madrid 2 Centro de Tecnología Biomédica. Universidad Politécnica de Madrid. Madrid 3 Departamento de Cardiología

Regenerativa. Centro Nacional de Investigaciones Cardiovasculares. Madrid

Mechanical properties of cells are key and influence their ability to migrate and their contribution to tissue development and regeneration. The effect of the mechanical cues in cell fate is particularly important in the case of stem cells [1] and, for them, stiffness could play a major role in their ability to migrate, which is crucial for tissue regeneration. However, this behavior has not yet been completely studied. Several methods, including magnetic twisting cytometry, optical tweezers, and cell indentation, have been used for the study of cell mechanical properties. Atomic force microscopy (AFM) has become a popular method for studying the mechanical properties of living cells allowing imaging them and analyzing locally their mechanical properties when cells are in physiologically relevant environments [2]. In this work, we have used AFM to carry out the mechanical behavior of cardiac stem cells, analyzing the relation of the elastic parameters to the region of the adherent cell studied and their variability. The study of the mechanical properties of these cells is considered important in the frame of the current works to identify routes to improve their ability to regenerate damaged cardiac tissue.

[1]. A. J. Engler, S. Sen, H. L. Sweeney and R. D. E. Discher, Cell 126, 677 (2006) [2]. M. Radmacher, R. W. Tillman, M. Fritz and H. E. Gaub, Science 257, 1900 (1992)

P24

Exploring Van Der Waals Interaction For Organic Macromolecules On Metal Surfaces

Ane Sarasola1,2

, Mikel Abadía3, Rubén González -Moreno

3,4, Celia Rogero

3,4, Aran

Garcia-Lekue2,5

1 Departamento de Física Aplicada I UPV/EHU, 48003, Bilbao, Spain 2 Donostia International Physics

Center (DIPC), 20018 San Sebastian, Spain 3 Centro de Física de Materiales (CSIC-UPV/EHU), 20018 San

Sebastian, Spain 4 Instituto de Ciencia de Materiales de Madrid (CSIC), 28049, Madrid, Spain 5 IKERBASQUE, Basque Foundation for Science, 48011, Bilbao, Spain

A deep understanding of the interaction between the building blocks of an organic/inorganic interface is key to control the engineering of such nanostructures. For this aim, a reliable description of the geometry and energy of the system is required. Although Density Functional Theory (DFT) has widely demonstrated its efficiency to describe the adsorption of organic molecules on metal surfaces using Generalized Gradient Approximation (GGA) functionals, recent developments including van der Waals (vdW) non local forces have provided a step further towards a trustworthy description of organic-molecule metal junctions[1]. Among all the vdWinclusive DFT schemes considered, vdW-dF (with its optB88 functional) and vdWsurf are reported to be the most accurate ones [2]. Motivated by recent STM experiments [3], we have compared the theoretical description of a macromolecule deposited on a reactive surface, such as phtalocyanines (H2Pc) and metalized phtalocyanines (CuPc) on Cu(110), using

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GGA and optB88-vdW functionals. On one hand, we have investigated the influence that the distortion of the molecule and the reconstruction of the surface may have on the binding energy curves and on the bonding mechanism[4]. On the other hand, we have gained insight into the interaction between the adsorbed molecule and surrounding extra Cu adatoms, which are known to be abundant on Cu (110) surfaces[5].

Figure: A) STM image and an illustration of H2Pc molecules adsorbed on Cu(110) surrounded by Cu adatoms. B) Atomic configuration of the H2Pc molecule on Cu(110). The different adatom adsorption sites considered in the calculations are represented by white numbered positions.

[1]. A.Tkatchenko, L.Romaner, O.T. Hofmann, E.Zojer, C.Ambrosch-Draxl, M. Scheffler, MRS bulletin 35, 435 (2010)

[2]. J.Carrasco, W.Liu, A.Michaelides, A.Tkatcehnko, J. Chem.Phys. 140, 084704 (2014) [3]. M.Abadía, R.González-Moreno, A.Sarasola, G.Otero, L. Floreano, A.Garcia-Lekue, C.Rogero, ACS Nano,

submitted (2014) [4]. P.Sony, P.Puschnig, D. Nabok, C. Ambrosch-Draxl, Phys.Rev.Lett. 99,176401 (2007) [5]. Matthew S. Dyer, Abel Robin, Sam Haq, Rasmita Raval, Jiří Klimeš, ACS Nano 5, 1831 (2011)

P25

Moirés on Graphene/Pt(111): low temperature NCAFM measurements and first-principles calculations

M. Ellner1, B. de la Torre2, P. Pou1,3, N. Nicoara2,4, J. M. Gómez-Rodríguez2,3, R. Pérez1,3

1Dept. Física Teórica Materia Condensada, Universidad Autónoma de Madrid, Spain 2Dept. Física Materia Condensada, Universidad Autónoma de Madrid, Spain

3Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Spain 4Iberian Nanotechnology Laboratory, Braga, Portugal

The epitaxial growth of graphene on metals is currently an active field of research [1]. Graphene on Pt(111) being of utmost interest due to the low interaction of its pristine surface with the metal resulting in moiré patterns with small topographic corrugation. Whereas the STM resolves the moirés through its dependence of the DOS [2], the system becomes a challenging one for the NCAFM and ideal for examining the sensitivity of this technique to local electronic variations.


In this work, for the first time, the graphene/Pt(111) system is studied with NCAFM both experimentally and theoretically. With a home-made AFM operating at 5K and UHV, atomic resolution, inversion of atomic contrast from a hexagonal to a triangular lattice, and different moiré patterns are observed. We explain these results with first-principle DFT calculations. The inversion of atomic contrast may be rationalized in terms of the electronic density dependence of the Pauli interaction [3]. However, we associate the AFM observation of the moiré to sub-surface resolution. The non-topographic corrugation of the moiré is obtained in the repulsive regime, where the tip indents the graphene sheet deep enough so the displaced carbon atoms act as a tip that allows sensing the Pt surface with atomic resolution. This idea may be generalized to other 2D materials opening the door to simultaneous monolayer/substrate AFM characterization.

[1]. A. J. Martínez-Galera, et al. Nano Lett. 11, 3576 (2011). [2]. M. M. Ugeda, et al. Phys Rev Lett. 107, 116803 (2011). [3]. Ondracek et al. Phys Rev Lett, 106, 176101 (2011).

P26

Magnetic Domain Structures In Single Modulated FeCoCu Nanowires

O. Iglesias-Freire1, E. Berganza1, C. Bran1, M. Vazquez1, A. Asenjo1

1 Instituto de Ciencia de Materiales de Madrid, Cantoblanco.

In this work, we present a Magnetic Force Microscopy (MFM) study on the domain configuration of single FeCo based cylindrical nanowires. FeCo nanowires exhibit the necessary capability to be employed in novel generation of rare-earth-free permanent magnets due to their high Curie temperature, large saturation magnetization and enhanced magnetic hardness [1]. High resolution MFM technique has been used to characterize isolated nanowires deposited onto Si substrates. The polycrystalline Fe28Co67Cu5 nanowires, growth by electrochemical methods into the anodic alumina membrane, present high shape anisotropy due to their high aspect ratio. Tailoring the membrane pore diameter we can prepare straight nanowires, as well as modulated nanowires with diameter varying periodically between 22 nm and 35 nm. MFM imaging allows us to conclude that the straight nanowires posse a dominant

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single domain behaviour even in the demagnetized state, while modulated ones -with increased hardness- show the presence of domain walls. Micromagnetic simulations [2] predict the magnetization to point along the wire main axis in both cases although two kinds of stable domain walls are expected for the modulated wires.

[1]. Bran et al., “Structural Dependence of Magnetic Properties in Co-Based Nanowires: Experiments and Micromagnetic Simulations,” IEEE Trans. Magn., vol. 49, no. 8, p. 4991,2013

[2]. OOMM, M. J. Donahue and D. G. Porter, National Technical Information Service Document No. PB99-163214, National Institute of Standards and Technology (NIST), September 1999

P27

Donor-acceptor Interactions At Solid Surfaces Controlled By Charge Transfer

Koen Lauwaet1, J. Rodríguez-Fernández

2, R. García

3, M. A. Herranz

3, N. Martín

1,3, J. M.

Gallego1,4

, R. Otero1,2, R. Miranda1,2

1 IMDEA-Nanociencia. Madrid. 2 Universidad Autónoma de Madrid. Madrid. 3 Universidad Complutense de Madrid. Madrid. 4 ICMM-CSIC. Madrid.

Organic charge-transfer (CT) complexes are molecular compounds mixing two species with different electron affinities: an electron donor (D) and an electron acceptor (A). Charge transfer processes between D–A complexes and metallic electrodes are at the heart of novel organic optoelectronic devices such as solar cells [1]. In contrast with the existing exhaustive study of the bulk properties of CT solids, very little is known about the thinfilm behaviour. The transition from bulk D-A complexes to ultra-thin films of monolayer thickness deposited on metals introduces a new phenomenology related to the organic– inorganic interface [2]. Effects like hybridization, CT with the surface and molecular level alignment become factors that may govern the electronic transport. Hence, the adsorption of an ultra-thin D–A layer on a metal opens a new field of research for the potential application of CT complexes as devices in the nanoscale. Simultaneous characterization of the interdependent structural and electronic properties is required for a thorough understanding of the D-A complexes under study [3]. Here, by combining both Scanning Tunnelling Microscopy (STM) and X-ray Photoelectron Spectroscopy (XPS) in situ, we can study the delicate balance that exists between intermolecular and molecule–substrate interactions, as well as the hybridization, and the charge transfer taking place in model donor–acceptor assemblies at metal-organic interfaces. By controlling the stoichiometry between tetrathiafulvalene (TTF, electron-donor) and tetracyanoethylene (TCNE, electronacceptor), we can tune both the structural and the electronic properties of a donor-acceptor system on Ag(111). We show that this system exhibits various structural phases, depending on the stoichiometry, each leading to different levels of charge transfer. Interestingly enough, the charge-transfer does not seem to follow a monotonic behavior with the D:A ratio. These results demonstrate that atomistic studies on the growth of organic thin films under ultrahigh vacuum (UHV) conditions can lead to the kind of accurate control needed in order to optimize device characteristics.

[1]. L. Bartels, Nat. Chem., 2, 87 (2010).


[2]. N. Gonzalez-Lakunza, I. Fernández-Torrente, K. J. Franke, N. Lorente, A. Arnau, and J. I. Pascual, Phys. Rev. Lett., 100, 156805 (2008)

[3]. D. G. de Oteyza, J. M. Garcıá-Lastra, M. Corso, B. P. Doyle, L. Floreano, A. Morgante, Y. Wakayama, A. Rubio, and J. Enrique Ortega, Adv. Funct. Mater., 19, 3567 (2009)

P28

Local Electrical Properties Of Double Terminated La0.7Sr0.3MnO3 Films

Laura López-Mir1, José Cisneros

1, Carmen Ocal

1, Lluís Balcells

1, Benjamín Martínez

1,

Laura López-Mir1

1 Institut de Ciència de Materials de Barcelona, ICMAB‐CSIC, Campus UAB, 08193 Bellaterra, Spain

La0.7Sr0.3MnO3 (LSMO) thin films were grown using sputtering technique onto STO substrates initially exhibiting either SrO or TiO2 single chemical termination or a mixture of both. A combination of tapping mode atomic force microscopy (AFM) and conductive AFM (CS-AFM) has been used to study the topography and the electric properties of the films. Though the deposited films are expected to grow following the stacking sequence of the substrate [1], all obtained LSMO films presented bimodal conducting properties typical of double terminated films, therefore indicating that the substrate termination has not been replicated at the thin film surface in our case. The possible influence of surface termination on the electrical properties of the films and the local induced resistive switching [2] using the AFM tip as top electrode has been explored. Finally, as resistive switching is crucially dependent on the electrode-film interface; several AFM probes with different conductive coatings have been used to study the influence of the current sensing tool in this phenomenon

P29

The Mode Of Growth And Magnetic Properties Of Ultrathin Co Films Grown On The Curved Pd(111) And Curved Ni(111)

A. Magaña1, M. Ilyn

2, L. Fernández

3, J. E. Ortega

1,2,3, F. Schiller

2

1 Departamento de Fisica Aplicada I, Universidad del Pais Vasco, E-20018 Donostia-San Sebastian, Spain 2 Centro de Fisica de Materiales (CSIC-UPV-EHU) and Materials Physics Center (MPC), E-20018 Donostia-

San Sebastian, Spain 3 Donostia International Physics Center, E-20018 Donostia-San Sebastian, Spain

Ultrathin Co films grown epitaxially on Pd(111) and Ni(111) demonstrate out-of-plane (OOP) magnetic anisotropy due to the strong interfacial effects. These materials were found to be useful for applications in spin-torque devices and bit-patterned magnetic media. Furthermore it is a suitable playground to study the interplay between the crystal structure, electronic and magnetic properties of the interfaces [1]. Though the mode of growth and magnetism of Co films have been thoroughly studied for flat Pd(111) and Ni(111), these properties are less investigated when the substrate is comprised by vicinal surfaces of these single crystals.

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Meanwhile stepped reconstructions of the vicinal surfaces alter the surface electronic states of the substrate and substantially affect the mode of growth of the overlayers. Also they were found to be a useful template for growth of the ordered nanostructures [2,3].

In this work we present results of study of the mode of growth and magnetic properties of the ultrathin Co films grown on the curved Pd(111) and curved Ni(111). We have used two large single crystals (9x9 mm2 and 12x12 mm2 respectively) polished so that the miscut angle toward the [112 ̅] or [1 ̅1 ̅ 2] direction changes smoothly from 0 to 11 and from 0 to 15 degrees, respectively. Since the width of the terrace of the reconstructed surface depends on the miscut angle it has allowed us to study the growth mode as a function of the terrace’s width in the range from 100 to 1 nm, and a Co coverage from submonolayer to few monolayers

Combined STM and LEED measurements at room temperature yielded systematic data on the variation of the structure and morphology of the Co films with miscut angle. In-situ MOKE measurements performed at room temperature and at 130 K complemented it with information about the magnetic anisotropy. Using of the substrates with relatively big (9% for Pd(111)) and small (2% for Ni(111)) lattice mismatch revealed the effect of the strain.

[1]. M. T. Johnson, P. J. H. Bloemenz, F. J. A. den Broeder, J. J. de Vries, Rep. Prog. Phys. 59, 1409 (1996) [2]. A. Mugarza, F. Schiller, J. Kuntze, J. Cordon, M Ruiz-Oses, J. E. Ortega, J. Phys.: Condens. Matter 18, S27

(2006) [3]. K. Kuhnke and K. Kern J. Phys.: Condens. Matter 15 (2003) S3311–S3335

P30

Neural Signatures Protocol In Artificial Neural Networks Used To Characterize The Electrostatic Signal In Conductive Thin

Films

Elena Castellano-Hernández1, Juan José Sáenz Gutiérrez

1, Sacha Gómez

1

1 Universidad Autónoma de Madrid. Spain

The use of scanning probe microscopy (SPM) to characterize and manipulate surfaces at the nanoscale usually faces the problem of dealing with systems where several parameters are not known. Artificial neural networks (ANNs) have demonstrated to be a very useful tool to tackle this type of problems. Here, we show that the use of ANNs allows us to quantitatively estimate magnitudes such as the dielectric constant of thin films or the amount of free charge that is present in the sample. To improve thin film dielectric constant estimations in EFM, we first increase the accuracy of numerical simulations by replacing the standard minimization technique by a method based on ANN learning algorithms. Second, we use the improved numerical results to build a complete training set for a new ANN. The results obtained by the ANN suggest that accurate values for the thin film dielectric constant can only be estimated if the thin film thickness and sample dielectric constant are known. Moreover, we demonstrate that the presence of free charge (i.e. A non-zero value for the conductivity) can change


dramatically the response of the microscope, making this fact a very important issue to take into account when quantitative values are being measured.

To get a deeper knowledge of the physical processes involved in the imaging of thin films by Scanning Probe Microscopy we use artificial neural networks to replace the full structure of a thin film over a dielectric substrate by an equivalent semiinfinite sample described only by an effective dielectric constant. For thin film thicknesses around 1 nm, we demonstrate that thin film dielectric constants between 1000 and 10 000 give very different electric responses. This effect is of great interest in the study of thin materials with a high polarizability such as graphene layers, where we find that for electrostatic purposes, a graphene layer is equivalent to an extremely thin dielectric layer with an effective permittivity that depends on the conductivity of the layer and spans from 5 for the insulating layers, to 2000 for the more conductive ones. ANN techniques such as neural signatures are used to improve the knowledge of the most relevant elements inside the EFM signal.

P31

Towards An AFM Study Of The Interaction Of Pseudomonas Aeruginosa With Multivalent Glycoclusters

F. Zuttion1, D. Sicard

1, C. Ligeour

2, Y. Chevolot

1, F. Morvan

2, A. Imberty

3, G. Vergoten

4,

S. Vidal5, J.J. Vasseur2, E. Souteyrand1, M. Phaner-Goutorbe1

1 Université de Lyon, Institut des Nanotechnologies de Lyon (INL, UMR CNRS 5270), site Ecole Centrale de Lyon, 36 avenue Guy de Collongue, 69134 Ecully, France 2 Institut des Biomolécules Max Mousseron,

Département des Analogues et Constituants des Acides Nucléiques (DACAN), UMR 5247 CNRS-UM1-UM2, Université de Montpellier 2, CC1704, Place E. Bataillon 34095 Montpellier Cedex 5, France 3

CERMAV (CNRS, UPR 5301), Universitè Joseph Fourier, BP53, Grenoble, France 4 Laboratoire de Glycobiologie Structurale et Fonctionnelle, (LGSF) UMR CNRS-Universitè de Lille 1, Cité scientifique-

Bâtiment SN3, 59655 Villeneuve d’Ascq Cedex, France 5 Université de Lyon, Institut de Chimie et Biochimie Moléculaires et Supramoléculaires (ICBMS, UMR CNRS 5246), Laboratoire de Chimie

Organique 2- Glycochimie, 43 boulevard du 11 Novembre 1918, 69622 Villeurbanne, France

Pseudomonas aeruginosa (PA) is one of the most common pathogen identified in respiratory track infections of fibrosis cystic patients [1]. It takes advantage of different molecular tools (virulence factors) to adapt and proliferate in the human lugs. A promising approach is to inhibit the virulence factors of PA and particularly two lectins PA-IL and PA-IIL to develop a new antibacterial therapeutic approach. Here, we present our results in which we focused on the interaction of the galactose specific tetrameric lectin PA-IL

[2] and tetrameric galactose molecules (galactococlusters) as possible inhibitors of PAIL’s activity in the infection process. We have used Atomic Force Microscopy (AFM) technique in order to investigate the molecular arrangement of the complexes formed by PA-IL and different galactoclusters, and we have demonstrated that the organization of the complex depends on the topology of the glycocluster and on the hydrophobic/hydrophilic behavior of the glycoside moiety [3]. Also Single-Molecule Force Spectroscopy experiments are ongoing

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and our preliminary results related to the characterization of the adhesion force between a functionalized AFM tip -at which the lectin is attached- and glycoconjugates anchored to silica surface via DNA Direct Immobilization [1], [4] will be discussed.

[1]. A. Goudot, G. Pourceau, A. Meyer, T. Gehin, S. Vidal, J.-J. Vasseur, F. Morvan, E. Souteyrand, and Y. Chevolot, Biosens. Bioelectron., vol. 40, no. 1, pp. 153–60, Feb. 2013.

[2]. G. Cioci, E. P. Mitchell, C. Gautier, M. Wimmerová, D. Sudakevitz, S. Pérez, N. Gilboa-Garber, and A. Imberty, FEBS Lett., vol. 555, no. 2, pp. 297–301, Dec. 2003.

[3]. D. Sicard, Y. Chevolot, E. Souteyrand, a Imberty, S. Vidal, and M. Phaner-Goutorbe, J. Mol. Recognit., vol. 26, no. 12, pp. 694–9, Dec. 2013.

[4]. M. Phaner-Goutorbe, V. Dugas, Y. Chevolot, and E. Souteyrand, Mater. Sci. Eng. C, vol. 31, no. 2, pp. 384–390, Mar. 2011.

This work was financially supported by ANR-12-BSV5-0020, Lyon Biopole. Plateform NanoLyon is acknowledged for its technical support

P32

Surface Characterization Of PEGylated Self-assembled Monolayers On Gold For Biosensors Applications

A. Garnier1, F. Zuttion

1, F. Palazon

1, Y. Chevolot

1, E. Laurenceau

1, G. Grenet

1, C.

Botella1, E. Souteyrand1, M. Phaner-Goutorbe1

1 Université de Lyon, Institut des Nanotechnologies de Lyon (INL, UMR CNRS 5270), site Ecole Centrale de Lyon, 36 avenue Guy de Collongue, 69134 Ecully, France

The health and agrifood sectors are now pushing the limits of instrumentation and are demanding fast analysis of multiple samples in real-time. Currently, the detection, quantification and characterization of low-concentration biomolecules in complex fluids (human plasma or food samples) require many preparation steps and cannot be done in real-time. Thanks to the development of new techniques such as Surface Plasmon Resonance Imaging (SPRI) or Surface-Enhanced Raman Spectroscopy (SERS) it is possible to attain these performances, since both are label-free and real-time detection methods. Nevertheless, these techniques require the providing of well adapted bioreceptors in order to obtain reproducible and reliable analysis. In our group, we fabricate these bioreceptors by taking advantage of the affinity of gold with thiols: thus, gold surfaces are functionalized with self-assembled monolayers (SAMs) in order to subsequently immobilize the biological probe able to specifically recognize the target compounds [1]. We tested different kinds of molecules to form the SAMs; in general they are constituted of a thiol group -that allows a covalent binding to the gold surface-, an alkyl-chain followed by a polyethylene glycol (PEG) chain of variable length and a head group that determines the hydrophobic/ hydrophilic nature of the SAM. In particular, we focused our attention on two head groups: the carboxyl group (COOH) and the methoxy group (OMe), since the former can be chemically activated in order to covalently graft the biological probe of interest and the latter can be used to avoid the non specific adsorption [2]. To improve the performances of bioreceptors, it is critical to ensure at each step that the chemical functionalization process leads to a well organized SAM. So, the morphological and chemical aspects of these surfaces have to be investigated both at micro


and nano scales before grafting biomolecules. To do that, we used complementary methods such as X-ray Photoelectron Spectroscopy (XPS), Polarization Modulation-Infrared Reflection Adsorption Spectroscopy (PM-IRRAS), contact angle and Atomic Force Microscopy (AFM). Among all these techniques, only the AFM allows us to analyze the samples at the nanoscale. Herein we present a set of results on the characterization and comparison of various SAMs on gold. In particular, the AFM investigation has allowed us to get into the homogeneity and the adhesion properties of the samples.

[1]. M. Veiseh, B.T. Wickes, D.G. Castner, M. Zhang Biomaterials 25 (2004) 3315-3324. [2]. J. Lahiri, L. Isaacs, J. Tien, G.M. Whitesides, Anal. Chem. 71 (1999) 777790. [3]. The ANR P2N (ANR-12-NANO-0016-04 - PIRANEX project) is greatly acknowledged for financial support;

CNANO Rhône-Alpes for PM-IRRAS funding; NanoLyon for providing gold samples

P33

Sublattice localized electronic states in atomically resolved graphene-Pt(111) edge-boundaries

P. Merino1, L. Rodrigo2, A. L. Pinardi3, J. Méndez3, M. F. López3, P. Pou2, R. Pérez2, J. A. Martín-Gago1,3

1Centro de Astrobiología INTA-CSIC, Madrid, Spain. 2Dpto. de Física Teórica de la Materia Condensada and IFIMAC, UAM, Madrid, Spain.

3Instituto de Ciencias de Materiales de Madrid, CSIC, Madrid, Spain.

Understanding the connection of graphene with metal surfaces [1] is a necessary step for developing atomically-precise graphene-based technology. In this work [2] we combine high resolution RT-STM experiments with DFT calculations and non-equilibrium Green's functions method to unveil the atomic structure of a border-like edge between a Pt(111) step and a graphene zigzag edge. We have managed to get atomic resolution not only on both the metal and the graphene but also on the boundary (see Fig. 1). The graphene edges minimize their strain by inducing a 3-fold edge-reconstruction on the metal side. The tendency to form passivated zigzag graphene terminations plays a relevant role in the formation and orientation of the stable Moiré patterns. Our combined approach reveals the interesting electronic properties of this nanoscopic system including the preservation of the G-edge state shifted to energies at about +0.8 eV above Fermi level, highly localized in one of the graphene sublattices and confined to the G-Pt interface. This state spreads out inside the first Pt row resulting in a high quality G-metal electric contact that could be relevant for designing future atomically precise graphene metal leads [3].

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Fig. 1 A) Experimental RT-STM image of a graphene flake on a Pt(111) step edge. B) Atomic structure of

graphene zigzag edge on a Pt step calculated by a DFT method based on VASP. C) STM image compared with the atomic structure calculated with DFT. D) Simulated STM profiles at constant height (2.75 Å) for different bias voltages.

[1]. P. Sutter et al, PRB, 80, 245411 (2009); Martínez-Galera et al., Nano Lett., 11, 3576 (2011). [2]. P. Merino, L. Rodrigo et al. Accepted in ACS Nano (DOI: 10.1021/nn500105a).

P34

Quantum Capacitance and Electromigration: A Theoretical Approach

C. Salgado 1, J.J. Palacios 1

1Universidad Autónoma de Madrid, Dep. Condensed Matter Physics, Madrid, Spain

In recent years electron transport through metallic contacts at the nanoscale has been studied theoretically and with experiments. The most studied quantity is the current along with its derivatives. However, this is not the only quantity that can be measured. Capacitance also gives valuable information about the electronic and structural properties of the nanocontacts. We are interested here in the Quantum Capacitance which depends on the density of states and measures the quantum contribution to the capability of a device to accumulate electrons. This quantity depends of the chemical nature, i.e., of the available atomic levels of the material. It also depends of the energy with which electrons are injected. Therefore, it has a quantum mechanical origin in contrast to the purely electrostatic one [1].

We used ab-initio calculations based on DFT methods and the Nonequilibrium Green's Function Formalism to simulate such systems. To introduce non-equilibrium conditions, we apply an external bias voltage, at which electrons are injected. Among the simulated systems, there are contacts from different metals. Non-voltage-symmetric charge distributions emerge of our calculations. This is a result of the absence of electron-hole symmetry. The distinctive DOS corresponding to each metal is determinant in the capacitance, as well as other transport properties.

Simulation of Gold atom electromigration between two contacts under applied bias

voltage.

Chemisorption

of H on Graphene.


We also studied how the charge distribution affects the nonequilibrium induced forces on the atoms. This allows us to explain the transfer of atoms between the metallic electrodes mediated by the bias voltage. This phenomenon is called electromigration. If an atom moves between the two biased contacts, there arise forces occurring on the atom. These appear due to the nonequilibrium charge distribution[2] . The free energy that describes an out of balance problem, loses the symmetry corresponding to equilibrium. This leads forces that can determine a preferred direction for the electromigration of the atoms.

The same procedure is used to investigate the behavior of other systems under non-equilibrium conditions. This is the case of hydrogen chemisorption on grapheme [3]. Recent STM-experiments show how the sign and the value of the applied voltage in the tip can tune whether chemisorption occurs or not.

[1]. S. Datta, Quantum Transport: Atom to transistor, (2005) 3932. [2]. T. Todorov, D. Dundas, Physical Review B 81, (2010) 075416. [3]. D.W. Boukhvalov, MI. Katsnelson, Physical Review B 77(3), (2008), 035427. I would like to thank to my advisor, Juan José Palacios, for his advice and for guiding me through the research.

I also would like to thank to Julio Gómez-Herrero, Elsa Prada and María Soriano, from the Universidad Autónoma de Madrid, and Carlos Untiedt, María José Caturla and Bernat Oliver, from the Universidad de Alicante, for their collaboration and support.

P35

Domain overlap in Ni/Cu/Ni films with perpendicular magnetization: role of defects and ferromagnetic coupling

Miguel Ciria1,2, Edna Corredor1,2, David Coffey1,2, José Luis Diez-Ferrez3 and José Ignacio Arnaudas 2,3

1Instituto de Ciencia y Materiales de Aragón CSIC-Universidad de Zaragoza, Zaragoza, Spain2Departamento de Física de la Materia Condensada, Universidad de Zaragoza, Zaragoza,

Spain.3Laboratorio de Microscopias Avanzadas, Universidad de Zaragoza, Zaragoza, Spain.

Magnetostatatic interaction between layers with perpendicular magnetization induces parallel alignment between the domains of each block unless an antiferromagnetic AF coupling exists between the blocks [1]. Here we show, by performing magnetic force microscopy images on Ni(tNi)/Cu(3 nm)/Ni(tNi) structures, with tNi = 3 and 4 nm, that a large area of the structure with tNi = 3 nm has an antiparallel (AP) domain configuration without the presence of AF coupling, and that the area of these unexpected structure decreases for tNi = 4 nm, see Figure. The energy Em of the magnetic configurations is obtained by calculating the magnetostatic energy for periodic domain configurations with only parallel (P) domains, and for configurations with parallel and antiparallel (P-AP) domains, as well as the domain wall density energy. Em is calculated numerically showing that the P domain configuration has the lowest energy. Nevertheless the energy difference between the P and the P-AP configuration, Em, for the Ni(3 nm)/Cu(3 nm)/Ni(3 nm), about 600 J/m3 is three times smaller than the value calculated for the Ni(4 nm)/Cu(3 nm)/Ni(4 nm) sandwich, about 2000 J/m3. We propose that the pinning of the domain walls by defects, such as threading dislocations, is able of stabilize the AP configuration in the Ni(3 nm)/Cu(3 nm)/Ni(3 nm) structure but fails to create the same

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configuration as tNi increases because, beside the increment of Em,, the shape of the minimum of Em as a function of the domain size changes from a shallow feature to a deep and well defined shape, leading to an increased domain size [2].

Figure. Magnetic force microscope image of a 4 nm thick nickel film (a), the Ni(3 nm)/Cu(3 nm)/Ni(3 nm) (b) and the Ni(4 nm)/Cu(3 nm)/Ni(4 nm) (c) structures.

[1]. N. S. Kiselev, I. E. Dragunov, U. K. Rößler, and A. N. Bogdanov, Appl. Phys Lett 91, 132507 (2007) [2]. G. Bochi et al. Phys Rev. Lett. 75, 1839 (1995)

P36

Characterization Of Trimethylamonium-based Ionic Liquid Surfaces With Scanning Force Microscopy

Jaime Colchero1, Jesús Sánchez-Lacasa

1, Pedro Lozano

2, Juana M. Bernal

2

1 Departamento de Física, Instituto Universitario de Investigación en Óptica y Nanofísica (IUIOyN), Universidad de Murcia 2 Departamento de Bioquímica y Biología Molecular B e Inmunología, Facultad de

Química, Universidad de Murcia

The objective of this work is to investigate the superficial structure of an ionic liquid family widely used in various fields of science to better understand the unique properties of these molten salts and their modern applications: energy storage devices, lubricants or solvents for nanoparticle stabilization, materials extraction or reactive catalytic supports among other uses. For this study we have used hydrophobic ionic liquids (ILs) based on trimethylamonium cations with long alkyl side-chains, [Cntma][Ntf2], with n=12, 14, 16 and 18, on top of a metallic substrate. For the nano-characterization of the surfaces we have used a Scanning Force Microscope working in the dynamic mode, finding large flat planes of nanometer thickness for all samples prepared indication nanocrystalline ordering . Thickness dependence with alkyl side-chain length has been also studied in detail in these compounds. When these ILs are deposited on a structured substrate (e.g. the metallic covering of a DVD) they fill up the tracks on the DVD and grow above them without flooding the available surface. The upper surface of these IL walls stay flat and exhibit a rich dynamics as shown in the pictures.


P37

Manipulation Of The Electronic Structure In A Ruthenium Complex By An STM/AFM Tip

Marten Piantek1, David Serrate

2,3, Jose Ignacio Pascual

4,5, Ricardo Ibarra

2,3

1 Instituto de Ciencia de Materiales de Aragón - ICMA-CSIC, Universidad de Zaragoza 2 Laboratorio de Microscopías Avanzadas - LMA, Universidad de Zaragoza 3 Departamento de Física de la Materia

Condensada, Facultad de Ciencias, Universidad de Zaragoza 4 IKERBASQUE, Basque Foundation for Science, Bilbao 5 CIC NanoGUNE, Donostia-San Sebastian

Metal- organic complexes are of high interest in a wide range of material science due to their magnetic properties. The electronic configuration of the metallic center that usually defines the magnetic state of the molecule strongly depends on the electric field induced by the coordinating ligands. Instead of axial molecular ligands we used the tip of an STM/ AFM sensor in order to manipulate the electronic structure of the metallic center of a squared-planar Ru(dibenzoylmethanate)2 complex. With force-distance measurements we traced the interaction pathway between the Ru ion and the tip, and found a discrete jump into contact. Scanning tunneling spectroscopy revealed a change of the density of states around the Fermi level and hence in the electronic configuration of the Ru ion after contact formation.

P38

Temperature Controlled Formation Of Metal-organic Assemblies On Surfaces

Marten Piantek1, David Serrate

2,3, Jose Ignacio Pascual

4,5, Ricardo Ibarra

2,3

1 Instituto de Ciencia de Materiales de Aragón - ICMA-CSIC, Universidad de Zaragoza 2 Laboratorio de Microscopías Avanzadas - LMA, Universidad de Zaragoza 3 Departamento de Física de la Materia

Condensada, Facultad de Ciencias, Universidad de Zaragoza 4 IKERBASQUE, Basque Foundation for Science, Bilbao 5 CIC NanoGUNE, Donostia-San Sebastian

On-surface chemical synthesis of organic species is a rapidly emerging tool in surface science for the in-situ creation of large organic compounds that cannot be produced in any other kind chemical synthesis. The demand for such materials is for example reflected by the effort that is being made on the development of extended metal-organic covalent networks as future materials in information technology. A recent approach in this direction, using so called steering reactions, starts from well ordered chemical templates in form of coordination networks [1]. By thermal activation the coordinative character of the network transforms into covalent while the network´s structural order persists. Chemical templates are only suitable if they are structurally stable at the activation temperature. For the development of suitable syntheses strategies a detailed understanding of the annealing process is hence inevitable. We followed the route of Abel et al. [2] and used a transition metal and the organic ligand Tetracyanobenzene (MnTCNB) as precursors for the metal-organic network. An extended

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temperature-dependent study of Mn-MnTCNB coordination networks on different substrates in view on their suitability as chemical templates was conducted. By means of variable temperature STM we monitored transitions between several apparent and occasionally exotic network phases in a range between room temperature and 400 °C. The substrate turned out to play a crucial role since at elevated temperatures the surface reactivity increases and hence the influence on the network´s integrity. Hence the chemical templates available for the covalent reaction and the resulting covalent compounds depend strongly on the choice of the substrate.

[1]. Lin, T.; Shang, X. S.; Adisoejoso, J.; Liu, P. N.; Lin, N. Journal of the American Chemical Society 2013, 135, 3576–3582.

[2]. M. Abel, S. Clair, O. Ourdjini, M. Mossoyan, and L. Porte, J. Am. Chem. Soc., 133, 1203 (2011). “Single Layer of Polymeric Fe-Phthalocyanine: An Organometallic Sheet on Metal and Thin Insulating Film”

P39

The Verge Of Antiferromagnetic RKKY Order Among Individual Kondo Impurities

María Moro-Lagares1, Marten Piantek

2, M. Ricardo Ibarra

1, José I. Pascual

1,3, David

Serrate1

1 INA-LMA, University of Zaragoza, Spain 2 ICMA, CSIC-University of Zaragoza, Spain 3 CIC-Nanogune,

Donostia-San Sebastián, Spain

The Ruderman-Kittel-Kasuya-Yosida interaction (RKKY) is the paradigm to build artificial spin systems with controllable coupling for applications in quantum and classical information processing. The control and read-out of the spin state in such devices by electric means entails necessarily contacting individual localized spins with metallic leads. In virtue of the antiferromagnetic exchange coupling with the lead conduction electrons, the localized spin is prone to become a Kondo screened spin-singlet, losing thereby its functionality. Thus, Kondo screening and RKKY mediated magnetic coupling of spins are mutually exclusive. Using a scanning tunneling microscope, we studied the phase transition between both regimes by performing spatially and energy resolved measurements of the Kondo resonance in artificial Co atomic structures over Ag(111). Our experiments demonstrate the coexistence of Kondo screening and RKKY correlations of localized 3d magnetic moments. Magnetic correlations are already noticeable for atoms 14.5 Å apart as a decrease of the Kondo resonance amplitude. At interatomic separations of 5.8 Å, the impurity spin becomes delocalized and an effective antiferromagnetic RKKY interaction of 2 meV arises. In order to suppress Kondo fluctuations in favor of magnetic order we have built Co clusters with controlled geometry and interatomic separation. We find a systematic splitting and vanishing of the Kondo resonance which depends on the magnetic ground state of each cluster in the absence of Kondo screening.


P40

Substrate/nanodot Exchange Coupling For Co Nanodot Arrays Grown On Rare Earth–Au (111) Based Nanotemplates

L. Fernández1, M. Blanco-Rey

1,2, M. Ilyn

3, L. Vitali

2,4, A. Magaña

6, A. Correa

1, P.

Ohresser5, J.E. Ortega1,3,6, A. Ayuela1,3, F. Schiller1,3

1 Donostia International Physics Center, 20018 Donostia-San Sebastián, Spain 2 Departamento de Física de Materiales, Universidad del País Vasco UPV/EHU, 20018 Donostia-San Sebastián, Spain 3 Centro de Física de Materiales (CSIC-UPV-EHU) and Materials Physics Center (MPC), 20018 San Sebastián, Spain 4

Ikerbasque, Basque Foundation for Science, 48011 Bilbao, Spain 5 Synchrotron SOLEIL,Saint-Aubin BP 48, 91192 Gif-sur-Yvette, France 6 Departamento de Física Aplicada I, Universidad del País Vasco UPV/EHU,

20018 Donostia-san Sebastián

Controlling and manipulating exchange coupling and anisotropy in patterned magnetic nanostructures is the key for developing advanced magnetic storage and spintronic devices. Scanning tunneling microscopy analysis of different rare earth (RE)-Au (111) surfaces reveals the formation of a trigon network that transforms with longer evaporation times into a RE-Au

2

surface alloy with 1-2 ML of thickness. Both structures are found to provide optimal nucleation points for the formation of hexagonal arrays of Co nanodots. In the case of Gd as RE, X-ray magnetic circular dichroism measurements reveal an antiferromagnetic coupling across the Co/nanotemplate interface. In the particular case of the GdAu

2 surface it is found that the

coupling is very strong, which is corroborated by full-potential linearized augmented plane wave calculations. These studies find that the anisotropy of the Co nanodots is profoundly modified by the influence of the GdAu

2 nanotemplate that induces large anisotropy values. In

clear contrast with non-magnetic Au substrates, GdAu2 triggers the early switch in the

anisotropy direction from out-of-plane in monolayer-thick Co, to in-plane, in bilayer Co films.

P41

Ultra High Vacuum PVD Graphene growth on Cu-foils from a C60 carbon source: growth and characterization

J. Azpeitia1, G. Otero-Irureta2, F. J. Mompeán1, B. Sánchez1, M. García-Hernández1, J. A. Martín-Gago1, C. Munuera1, M. F. López1

1 Instituto ciencia de Materiales de Madrid-CSIC, Madrid, Spain 2 Universidad de Aveiro, Portugal,

The production of high-quality inexpensive graphene is an absolutely necessary first step for the material to ever live up to its promise in commercial applications. Among the different growth methods reported to date, physical vapor deposition (PVD) from a suitable organic precursor emerges as an advantageous procedure since lower substrate temperatures are required to produce graphene [1-2]. On the other hand, particularly attractive is the use of low

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carbon solubility Cu substrates for graphene growth, owing to its inexpensiveness and the possibility of post-growth graphene transfer on arbitrary substrates [3].

In this work, we present the growth of graphene layers by PVD under ultra-high vacuum conditions on polycrystalline 25 μm oxygen-free Cu foils. We used as carbon source a C60 evaporator maintained at 500 ºC. Prior to carbon evaporation the Cu foils have been treated by Ar-sputtering and thermal annealing cycles in order to clean them and promote the growth of well oriented large Cu terraces, especially suitable for LEED analysis (figure 1). After graphene growth is complete, sample analysis is performed with different techniques to characterize the structure and quality of the graphene layer. In-situ LEED images show well defined Cu (111) and (100) reflections and rings corresponding to graphene in various orientations with respect to the Cu grains (figure 1). Ex- situ Atomic Force Microscopy (AFM) and Raman spectroscopy are employed to gather information on sample morphology and quality (figure 1). We are currently optimizing graphene transfer from our samples to insulating oxide substrates with aim to determine its bandgap and macroscopic and local magnetotransport properties.

Figure 1: (a) AFM topographic image of a Cu foil substrate before and (b) after cleaning treatments and graphene deposition. (c) LEED image of as-grown graphene on Cu-foil showing a (111) domain grain measured with 100 eV. (d) Raman spectra of graphene covered Cu foil.

[1]. X. Li et al, Science 324, 1312 (2009) [2]. R. Hawaldar, et al, Sci. Rep. 2, 682 (2012) [3]. S. Bae et al, Nat. Nanotechnol. 5, 574 (2010)

P42

Unusual Surface Faceting Induce by Metal Organic Complexes

M. Abadia1, R. González-Moreno 1, A. Sarasola 1,2, G. Otero 3, A. Verdini4, L. Floreano 4, A. Garcia-Lekue 1,5, and C. Rogero 1


1 Centro de Física de Materiales (CSIC-UPV/EHU) and DIPC, E-20018 San Sebastian, Spain2Departamento de Física Aplicada I UPV/EHU, 48003, Bilbao, Spain3Instituto de Ciencia de Materiales de Madrid (CSIC),

28049, Madrid, Spain4Istituto Officina dei Materiali (CNR-IOM), Laboratorio TASC,Trieste, Italy5Ikerbasque; Basque Foundation for Science; E- 48011; Bilbao; Spain

The actual demand of increasingly smaller devices drives the endeavors to explore new methods to miniaturize the designs. Thus, the development of methods capable of producing ordered nanostructured surfaces is a stimulating field.

In this context, a novedous molecular/substrate interaction mechanism that derives in a unique adsorbate induce surface reconstruction is presented. In particular we show how metalated phthalocyanines can promote the formation of regular arrays of Cu nanoribbons on its (110) surface.

At variance with the conventional changes of metal reconstructions upon molecular adsorption observed so far, the presented faceting is found to involve a massive reorganization of Cu adatoms. Thus, the energy gain of the final system comes not only from the preferential adsorption position of phthalocyanines on the copper surface, but also from their interaction with the sourrounded adatoms.

By combining experimental (Scanning Tunneling Microcopy) and theoretical surface science techniques we demostrate that indeed the mechanism behind the massive surface reshaping involves a molecular mediated uni-directional blocking of diffusing surface adatoms followed by their capture and accumulation.

[1]. M. Abadia, R. González-Moreno , A. Sarasola , G. Otero , A. Verdini, L. Floreano , A. Garcia-Lekue , and C.

Rogero, ACS Nano. (2014) SUBMITTED

P43

Search For A Gap-less Dangling Bond Wire.

Mads Engelund1, Daniel Sanchez-Portál

1, Thomas Frederiksen

2, Aran Garcia-Lekué

2

1 Centro de Física de Materiales, , Donostia - San Sebastián 2 Donostia International Physics Center, Donostia-San Sebastián

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STM induced hydrogen desorption is a method for making patterns with atomic precision on the Si (001):H and Ge(001):H surfaces. This technique can open pathways for surface electronic devices controlled with atomic precision. The dangling bond defects on the surface can be used as templates for further processing steps, e.g., attaching molecules to form a molecular wire. Still, it would be desirable to largely avoid these extra steps and use exclusively the dangling bonds for fabricating flat nanometer scale devices. However, the 1D structures formed by dangling bonds are prone to suffer from instabilities that open a band gap in the wires.

We have theoretically investigated dangling bond structures on Si(001):H and Ge(001):H with the aim of finding a ballistically conducting wire without a band-gap. Different levels of doping have been explored to see if the Fermi level can be manipulated without fundamentally changing the electronic structure of the wires, thus allowing to move the Fermi level away from the gap. Our conclusion is that such an approach is possible for Ge, while for Si the wire electrons have a strong tendency localize and open new band gaps.

Figure: Isosurface of the DOS of the 1D band formed in the band gap of the Ge(001):H surface when a line of hydrogen atoms are removed

P44

On-surface chemistry: cyclodehydrogenation of PAH catalyzed by metal surfaces.

I. Palacio1, A.L. Pinardi1, G. Otero-Irurueta1, J.I. Martinez1, M.F. López1, J. Méndez1, J.A. Martín-Gago1

1 Instituto de Ciencia de Materiales de Madrid ((ICMM), Madrid, Spain

One of the main goals in nanotechnology is to assemble low dimensional molecular networks in order to create new nano-objects. For that purpose, on-surface chemistry is one of the most powerful and suitable bottom-up approaches that can be employed. Dehydrogenation reactions of polycyclic aromatic hydrocarbons (PAH) catalyzed by metal surfaces allow a control at the atomic level of the resultant outcome, with the correct choice of the geometry of the precursor and on the type of metallic surface1.


In this work, we show that the strength of the PAH-substrate interaction rules the competitive reaction pathways (cyclodehydrogenation versus dehydrogenative polymerisation). Starting from the same molecular precursor (C57H33N3 or C40H24N2 (DiPy[5]DBH) and controlling its diffusion by the nature of the supporting surface (Au(111) or Pt(111)), temperature-triggered dehydrogenation takes place to provide molecular or polymeric structures of variable dimensionality2-3.

Combining advanced in-situ surface techniques as STM and NEXAFS with theoretical ab-initio calculations we have been able to achieve a complete understanding of the self-assembling of molecular precursors on surfaces. By merging information from these techniques and different single-crystal metal substrates, we report on the diffusion control of competitive intramolecular and intermolecular dehydrogenative processes respectively called cyclodehydrogenation and dehydrogenative polymerisation, which operate in the on-surface synthesis of N-doped fullerene, nanographene, polyaromatic network, membrane or grapheme (Fig. 1). By choosing the appropriate N-heteroaromatic precursors and by controlling their diffusion, the on-surface (cyclo)dehydrogenation can either lead to monomolecular triazafullerenes and diazahexabenzocoronenes (N-doped nanographene), or to N-doped polymeric networks.

Fig. 1: The heteroaromatic precursors 1 and 4 subjected to controlled on-surface dehydrogenation. 1 and 4 may form respectively (i) N-doped triazafullerene 2 or 2,5-diazahexabenzocoronene 5 (through intramolecular cyclodehydrogenation) or (ii) branched 2D polyaromatic architectures 3 or 6 (both through intermolecular dehydrogenative polymerisation and intramolecular cyclodehydrogenation).

Méndez, J.; López, M. F.; Martín-Gago, J. A., Chem. Soc. Rev. 40, 4578 (2011). A.L. Pinardi, G. Otero-Irurueta, I. Palacio, J.I. Martinez, B. Gomez-Lor, A. Jančařík, I.G. Stará, I. Starý, M.F.

López, J. Méndez, J.A. Martín-Gago. ACS Nano. 7, 3676(2013). A.L. Pinardi, J.I. Martinez, A. Jančařík, I.G. Stará, I. Starý, M.F. López, J. Méndez, J.A. Martín-Gago. Chem.

Commun., 50, 1555 (2014)

P45

Substrate-Induced Stabilization And Reconstruction Of Zigzag Edges In Graphene Nanoislands On Ni(111)

M. Olle1,2

, A. García-Lekue6, D. Sánchez-Portal

3, J.J. Palacios

4, A. Mugarza

1, G. Ceballos

1,

P. Gambardella1,2,5

1 Catalan Institute of Nanoscience and Nanotechnology (ICN2), UAB Campus, E-08193 Bellaterra

(Barcelona), Spain; 2 Department of Materials, Eidgenössische Technische Hochschule (ETH) Zurich, Schafmattstrasse 30, CH-8093 Zurich, Switzerland; 3 Donostia International Physics Center (DIPC), Paseo

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Manuel de Lardizabal 4, E-20018 San Sebastian, Spain, and Centro de Fisica de Materiales CFM-MPC, Centro Mixto CSIC-UPV, Apdo. 1072, San Sebastian, Spain; 4 Departamento de Física de la Materia

Condensada, Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain; 5 Instituciò Catalana de Recerca i Estudis Avancats (ICREA), E-08193 Barcelona, Spain; 6 Donostia International Physics Center

(DIPC), Paseo Manuel de Lardizabal 4, E-20018 San Sebastian, Spain, and IKERBASQUE, Basque Foundation for Science, E-48011, Bilbao, Spain

A combination of high resolution scanning tunnel microscopy and density functional theory (DFT) has been used to investigate the atomic structure of triangular and hexagonal graphene nanoislands on Ni(111). Due to the 1x1 stacking of graphene on Ni(111), this system is an ideal candidate to study the interaction between the metallic substrate and the graphene edges. Both triangular and hexagonal graphene islands are found to possess a top-fcc stacking with zigzag edges. Moreover, we show that the substrate has a determinant effect on the stabilization and reconstruction of zigzag edges, and can selectively influence the edge structure. Interestingly, we reveal that the reconstruction of the edge is determined by the registry of the edge carbon atoms with the substrate. This is clearly seen for the hexagonal islands, where half of the edges present a zigzag structure, while the other half show a pentagon-heptagon reconstruction. Based on our DFT calculations and predictions of the islands shape, we speculate that the energy barriers associated with the edge reconstruction could control the formation of either triangular or hexagonal islands depending on the exact growth conditions.

P46

Adsorption site dependence of vibrational excitations of molecular hydrogen

E.Carbonell1, M. Corso1,2, J. Li1, M. Borinaga1, J.I. Pascual1,2 1CIC nanoGUNE, 20018 Donostia-San Sebastián, Basque Country, Spain2IKERBASQUE, Basque

Foundation for Science, 48011 Bilbao, BasqueCountry, Spain


Transition-metal phtalocyanines are a well-known class of molecules used as model to study the interaction between metal surfaces and metal-organic compounds [1][2]. These kind of metal-organic complexes present a wide range of properties and functionalities which depend on the coordination of their central metal ion, such as magnetism or the adsorption of small gas molecules [3]. In this work we study Chlorinated Manganese Phtalocyanine (Cl-MnPc) molecules deposited on a Ag (111) substrate. We explore the adsorption characteristics of this system by means of a combined Low Temperature Scanning Tunneling and Atomic Force Microscope. After deposition on a room temperature substrate, a fraction of (dechlorinated) MnPc molecules coexist with Cl-MnPc on the surface. Moreover, Cl-MnPc can be controllably dechlorinated after the evaporation process. We find that both molecules are a preferential site of adsorption for molecular Hydrogen, which is known to present a bistable vibrationally mediated behavior depending on its different adsorption configurations [4]. Inelastic tunneling of electrons from a STM can excite such bistability which induces a fingerprint close to zero-bias on differential conductance measurements. Additionally, force spectra reveal differences on the electrostatic forces exerted between the tip and the molecule when the tunneling electrons trigger such hydrogen fluctuations. We find that these fingerprints are strongly modified by the presence or absence of Chlorine atoms in the phtalocyanine molecules.

Figure 1: STM image of a self assembled island of Cl-MnPc. MnPcs coexist both in the island and in the Ag (111) surface

A. Mugarza, R.Robles, C.Krull, R. Korytár, N. Lorente, and P. Gambardella, Phys. Rev B 85, 155437 (2012) Ying-Shuang Fu, Shuai-Hua Ji, Xi Chen, Xu-Cun Ma, Rui Wu, Chen-Chen Wang, Wen-Hui Duan, Xiao-Hui Qiu, Bo

Sun, Ping Zhang, Jin-Feng Jia, and Qi-Kun Xue, Phys. Rev. Lett. 99, 256601 (2007) K. Seufert, W. Auwärter and J.V. Barth, J. Am. Chem. Soc. 132, 18141-18146 (2010) C. Lotze, M. Corso, K.J. Franke, F. von Oppen and J.I. Pascual, Science 338, 779 (2012)

P47

2D To 1D Transition Of Surface States Investigated On Bismuth Curved Crystals

Jorge Lobo-Checa1, Federico Mazzola2, Luca Barreto3, Frederik M. Schiller1, Justin W. Wells2, Nicholas C. Plumb4, Johan Adell5, Philip Hofmann3, J. Enrique Ortega1,6

1Centro de Física de Materiales (CSIC/UPV-EHU), Manuel Lardizábal 5, E-20018 San Sebastián, Spain; 2Department of Physics, Norwegian University of Science and Technology (NTNU), N-7491 Trondheim,

Norway; 3Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO), Aarhus

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University, 8000 Aarhus C, Denmark; 4Swiss Light Source, Paul-Scherrer-Institut, 5232 Villigen,

Switzerland; 5MAX IV Laboratory, Lund University, P.O. Box 118, 221 00 Lund, Sweden; 6Departamento Física Aplicada I, Universidad del País Vasco, E-20018 Donostia-San Sebastián, Spain

Bismuth is a semimetal whose surface shows better metal behaviour than its bulk counterpart due to the presence of metallic-like surface states. These are spin-split given its large atomic weight and spin orbit interaction [1]. Depending on the crystal termination these states behave as two dimensional (2D), delocalized states, or one dimensional (1D), localized states [2]. Such modification of the electron wavefunction is induced by the presence of step arrays, by repulsive scattering at steps and confinement within terraces [3] and has been widely explored for Shockley states in noble metals [3-8]. Semimetals have not received such a widespread attention but the investigating of this 2D to 1D transition is particularly interesting since Bi is very close to being a topological insulator and great interest has emerged in topologically guaranteed 1D surface states.

We present a study that finely explores the 1D - 2D transition in Bismuth surface states using a curved crystal (see Fig. 1). Such special samples allows for a smooth variation of the surface orientation, which translates into a smooth variation of the step separation, i.e. the step potential barriers. The evolution of the electronic structure is investigated by state-of-the-art ARPES and correlated to the local structure obtained from STM and LEED. We find that this transition is very different from the noble metal curved surfaces because we do not observe umklapps and also the surface states are referred to the rhombic (111) direction of the crystal instead of the projection of the L point on the surface. Such results, to our knowledge, have never been reported.

Ph. Hofmann, Prog. In Surf. Sci. 81,191 (2006). J. W. Wells et al., Phys. Rev. Lett., 102, 096802 (2009). L. Bürgi et al., Phys. Rev. Lett. 81, 5370 (1998). A. Mugarza et al., J. Phys. Cond. Matt. 15, S3281 (2003). M. Corso et al., J. Phys. Cond. Matt. 21, 353001 (2009). J. E. Ortega et al., Phys. Rev. B 83, 085411 (2011). J. E. Ortega et al., Phys. Rev. B. 87, 115425 (2013). J. Lobo-Checa et al., Phys. Rev. B, 84, 245419 (2011).


P48

A Toolbox For Controlling Quantum States In Organic Monolayers

Bernhard Kretz1, David A. Egger1, Egbert Zojer1

1 Institute of Solid State Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria

The possibility of controlling interface properties “at will” holds a high promise for hybrid electronics and spintronics applications. Covalently-bonded selfassembled monolayers (SAMs) are very well suited for such interface modifications, as they offer a high flexibility regarding the design of their electronic properties. For example, the distribution of dipolar groups along the backbones of thiolate-bonded self-assembled monolayers has been shown to cause a modification of the electron wave-function and the vacuum level1. In particular, molecular orbitals like the highest occupied molecular orbital (HOMO) and the lowest unoccupied orbital (LUMO) get shifted in energy and localized on opposite ends of the molecular layer2. The latter can, for example, be interesting for separating electrons and holes in a device. Embedding radical groups in SAMs3,4 could be of interest for spintronics devices by enabling spin polarized transport5. Building on these results, in this work we perform band structure calculations using density functional theory on tolanthiolate-based SAMs where dipolar and radical groups are distributed along the SAMs. The aim of distributing different functional units along the backbones of SAMs is the development of a toolbox for controlling interface properties. Our results show that collective electrostatic effects induced by dipolar elements can help achieving localization of orbitals in a specific manner and, moreover, can be used to build quantum-cascade and quantum-well like structures. Furthermore, we suggest that embedding radical groups enables spin sensitivity in specific regions of an organic monolayer.

[1]. D. A. Egger, F. Rissner, G. M. Rangger, O. T. Hofmann, L. Wittwer, G. Heimel, and E. Zojer, Phys. Chem. Chem. Phys., 2010, 12, 4291–4294

[2]. F. Rissner, D. A. Egger, A. Natan, T. Körzdörfer, S. Kümmel, L. Kronik, and Egbert Zojer, J. Am. Chem. Soc. 2011, 133, 18634

[3]. G. Heimel, E. Zojer, L. Romaner , J.-L. Brédas and F. Stellacci, Nano Lett., 2009, 9 (7), pp 2559–2564

[4]. N. Crivillers, C. Munuera, M. Mas-Torrent, C. Simão, S. T. Bromley, C. Ocal, C. Rovira, and J. Veciana, Adv. Mater. 2009, 21, 1177–1181

[5]. S. Chakrabarti and A. J. Pal, Appl. Phys. Lett. 104, 013305 (2014)

P49

Cementing Proteins Provide Extra Mechanical Stabilization To Viral Cages

M. Hernando-Pérez1, S. Kruse2, E. Nakatani2, C. E. Catalano2, P.J. de Pablo1

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1 Departamento de Física de la Materia Condensada and Condensed Matter Physics Center (IFIMAC),

Universidad Autónoma de Madrid 28049 Madrid, Spain; 2 Department of Medicinal Chemistry, School of Pharmacy, University of Washington, H-172 Health Sciences Building, Box 357610, Seattle, WA 98195

The study of virus shell stability is key not only for gaining insights into their biological cycle, but also for using viral capsids in materials science. The strength of viral particles depends profoundly on their structural changes occurring during maturation, whose final step in many capsids requires the specific binding of decoration proteins to the viral shell. Therefore, we have characterized the mechanical stability of gpD-free and gpD-decorated bacteriophage lambda capsids. Our data demonstrate that the incorporation of gpD protein into the lambda shell imparts a major mechanical reinforcement that resists punctual deformations. We further interrogated lambda particles stability with molecular fatigue experiments, which resemble the sub-lethal Brownian collisions of virus shells with macromolecules in crowded environments. These novel results show that decorated particles are especially robust against collisions of a few kBT, which approximate those anticipated from molecular insults in the environment.

P50

Doping Of The Surface Of A Topological Insulator With Co Adatoms

M. C. Martínez-Velarte1,2, M. Moro-Lagares1,2, Trevor M. Riedemann3, Thomas A. Lograsso3,4, L. Morellón1,2, M. R. Ibarra1,2, D. Serrate1,2

1 Instituto de Nanociencia de Aragón (INA) and Laboratory for Advanced Microscopy (LMA), University

of Zaragoza, Spain; 2 Dpto. de Física de la Materia Condensada, Universidad de Zaragoza, Spain; 3 Ames

Laboratory, Ames, IA 50011, USA; 4 Department of Materials Sciences and Engineering, Iowa State University, Ames, IA 50011 USA

Topological Insulators (TIs) are a new electronic state of matter which has been amply investigated during the last years due to its unique properties which have great potential for spintronic applications. TIs are materials with a bulk energy gap and metallic surface states [1]. Due to time-reversal symmetry and spinorbit coupling, these surface states behave as Dirac Fermions and exhibit a peculiar k-dependent spin-texture. As a result, electron backscattering becomes quantum-mechanically prohibited, and surface states are expected to be robust against non-magnetic impurities or defects.

A large number of Bi-based ternary compounds have been theoretically predicted and experimentally proved to be topological insulators. Band structure calculations of Bi2Se2Te have predicted a TI state, with an isolated Dirac Point [2]. ARPES measurements of the occupied density of states (DOS) near the Fermi level support this calculations [3]. Here we show low temperature (4.7 K) Scanning Tunnelling Microscopy (STM) and Spectroscopy (STS) measurements on a Bi2Se2Te crystal, gaining large spatial resolution of both the occupied and unoccupied local DOS. The crystals were grown by the Bridgman technique. Atomically resolved STM images of the crystal surface shows a binary chemical contrast which is likely due


to Te and Se segregation in regions of a few nm in size. Our STS data is fairly dependent on positioning the tip over Te or Se regions.

Moreover, individual Co atoms were deposited on the crystal surface held at T<6K to prevent atom diffusion. Despite of the low crystal temperature during evaporation, adatoms and subsurface substitutional defects were found. The former shows an atomic resonance peak on the STS spectra at around -650 mV. Importantly, valence and conduction bulk bands undergo a shift towards lower energies upon Co doping.

In conclusion, we have succeeded in doping the 2-D topological surface states of Bi2Se2Te in the range of dispersed magnetic atoms. Our energy resolved STS measurements unveil its impact on the bulk electronic bands and the dispersion relation of the surface Dirac-fermions.

[1]. M. Z. Hasan et al., Rev. Mod. Phys., vol. 82, no. 4, pp. 3045–3067, Nov. 2010. [2]. M. Z. Hasan et al., Phys. Rev. B, vol. 85, no. 23, p. 235406, Jun. 2012. [3]. L. Bao et al., Sci. Rep., vol. 2, p. 726, Jan. 2012.

P51

Probing the magnetic interaction between single Cr atoms

Zsolt Majzik1, José Ignacio Pascual1,2

1CIC nanoGUNE, Donostia-San Sebastián, Spain

2Ikerbasque, Basque Foundation for Science, Bilbao, Spain E-mail: [email protected]

In the last decade it has been shown that magnetic properties of a single atom can be probed by inelastic electron tunneling spectroscopy [1]. In addition, magnetic nanostructures have been routinely assembled via atomic manipulation [2]. In the tunneling junction, spin excitation is induced if the bias voltage exceeds the threshold energy for excitation. The spin excitation process allows the electrons to tunnel inelastically leading to a stepwise increase in the conductance over the threshold bias [1,2].

Here we aimed to study the magnetic characteristics of isolated Cr atoms adsorbed on Cu2N/Cu(100) surface. Cr atoms were deposited and their properties were investigated at 1.1 K in a SPECS JT STM that has a magnetic field up to 3 T perpendicular to the sample.

Different inelastic tunneling spectra were observed over Cr atoms adsorbed on N sites than on Cu sites. In the first case we interpret our spectra as interplay between spin excitation and Kondo screening effect, which appears here at larger biases. However, if the Cr atom adsorbed on the Cu site, the Kondo effect does not appear in the spectra, only a spin excitation has a contribution near the Fermi level. Our results suggest that the spin configuration of the Cr atom varies among different adsorption positions.

By atomic manipulation we have constructed Cr dimers with different interatomic spacing (see Fig). Among the investigated pairs, the strength of the coupling, J, was the strongest when the Cr atoms were occupying the nearest Cu sites separated by a single N atom (JA). The coupling becomes significantly weaker if the Cr atoms are placed diagonally (JB). Interestingly, increasing further the interatomic separation induces less significant quench in the coupling energy (JC).

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In a dimer, the close proximity of the Cr adatoms induces a local crystal strain. Beside the variation in the strength of the magnetic exchange interaction, the strain-enhanced anisotropy has a strong impact on the stability of the antiferromagnetic coupling [3]. The combination of both effects explains well our large variation of J.

[1]. A. J. Heinrich, J. A. Gupta, C. P. Lutz, D. M. Eigler, Science 306, 466 (2004) [2]. C. F. Hirjibehedin, C. P. Lutz, A. J. Heinrich, Science 312, 1021 (2006) [3]. B. Bryant, A. Spinelli, J.J. T. Wagenaar, M. Gerrits and A. F. Otte, Phys. Rev. Lett 111, 127203 (2013)

P52

Are Textbooks Always Right? An AFM Search For Protein Packing Defects In Viruses

Aitziber Eleta-Lopez1, Alba Centeno2, Amaia Pesquera2, Amaia Zurutuza2, Christina Wege3, Alexander M. Bittner1,4

1 CIC nanoGUNE, Donostia-San Sebastián, Spain

2 Graphenea, Donostia-San Sebastián, Spain

3 Universität Stuttgart, Germany

4 Ikerbasque, Bilbo, Spain

Tobacco mosaic virus (TMV) is the first isolated and characterized virus [1, 2]. It is also one of the simplest viruses, composed of a single strand of helical RNA, embedded in a helix of 2130 identical coat proteins. In comparison with most other viruses, its biology, chemistry, and structure are known to exceptional details. This has made TMV a textbook example for viruses, protein complexes, and nanotubes. TMV measures 300 nm in length and 18 nm in diameter [3]. The helix pitch (protein-protein distance) is 2.29 nm, determined by X-ray fiber diffraction and cryo-EM of pure TMV, and by TEM of stained TMV (modified by heavy metal ions), but not yet by imaging techniques, such as scanning probe [4-7]. Thus, some questions arise: Is this a technical problem? Do the diffraction and averaging techniques overlook local defects? In this work, TMV has been imaged by AFM on different flat substrates such as mica, graphite, graphene and gold. In all the cases the virus length is about 300 nm, but the height varies depending on the surface. Less than 15 nm is obtained for hydrophilic mica and gold, but about 17 nm for graphite and graphene. High-resolution topography and phase images show a stripe-like irregular structure with a pitch of 7-12 nm (figure 1), which is incompatible with the


textbook data. The study is complemented by imaging the virus with ultra-sharp tips, and by experiments carried out at various humidity levels.

Figure 1. Phase image of TMV on mica at low humidity environment

[1]. D. Ivanowski, St Petersb. Acad. Imp. Sci. Bull. 35(1892) 65- 70. [2]. M. W. Beijerinck, Verh. Kon. Akad.Wetensch. 5 (1898) 3-21. [3]. J.M. Alonso, M.Ł. Górzny , A.M. Bittner, Trends Biotech. 31(2013) 530-538 [4]. A. Kendall, M. McDonald, G. Stubbs, Virology, 369(2007) 226–227 [5]. Daniel K. Clare, Elena V. Orlova, J. Strut. Biol. 171 (2010) 303–308 [6]. Roy Markham, J. H. Hitchborn, G. J. Hills, Simon Frey, Virology, 22(1964) 342- 359 [7]. Shu-wen W. Chen, Michael Odorico, Matthieu Meillan, Luc Vellutini, Jean-Marie Teulon, Pierre Parot,

Bernard Bennetau, Jean-Luc Pellequer, Nanoscale, 5(2013) 10877–10886

P53

A Theoretical DFT Study Of Unusual Moiré Patterns In The Graphene/Rh(111) System

Ana Martín-Recio1, Antonio J. Martínez-Galera2, José María Gómez-Rodríguez1, Carlos Romero-Muñiz3, Pablo Pou3, Rubén Pérez3

1 Dpto. Física de la Materia Condensada, U. Autónoma de Madrid, Madrid, Spain

2 Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, Köln, Germany

3 Dpto. Física Teórica de la Materia Condensada, U. Autónoma de Madrid, Madrid, Spain

The growth of graphene on transition metals by means of different techniques has been intensively studied in recent years [1]. The interaction with the metal not only changes the electronic properties of graphene, but also influences its geometrical structure, leading in many cases to periodic Moiré patterns. When the graphene-metal interaction is weak, several Moiré structures with quite different unit cell sizes are present [2]. On the contrary, in cases where the interaction is stronger, a single Moire structure tends to dominate. Graphene on Rh(111), with a 12x12 Moiré structure (11x11 for the Rh(111) substrate) well characterized by experimental techniques (LEED and UHV-STM) [3] and ab initio DFT calculations [4] was considered so far to be one of these latter cases [1]. In this work, we report the existence of new smaller Moiré patterns in the graphene/Rh(111) system identified by VT-STM. These structures, with very different periodicities, are stable and coexist with the 12x12 Moiré reported so far. The apparent corrugation of graphene in these structures seems to increase with the unit cell size of the Moiré pattern. In order to characterize the graphene-Rh interaction and understand the origin of this trend, we have carried out a systematic DFT study

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of these new structures (fig.1). Theoretical STM images have been calculated using both a simple Tersoff-Hamann approximation and a more sophisticated Green-Keldysh transport formalism. Only a proper calculation of the tunneling current, including explicitly the tip structure and electronic properties, provides theoretical corrugations in good agreement with the experiment.

Figure 1: Heights maps (in Å) of two Moiré patterns of different sizes.

[1]. M. Batzill. Surface Science Reports 67, 83 (2012) [2]. A. J. Martínez-Galera, I. Brihuega, J. M. Gómez-Rodríguez. Nano Letters 11, 3576 (2011) [3]. E. N. Voloshina, et. al. Applied Physics Letters 100, 241606 (2012) 4. M. Iannuzzi, J. Hutter. Surface Science

605, 1360 (2011)

P54

DFT study of AFM metal oxide imaging modes: Towards atomic species identification

Diego R. Hermoso1, Milica Todorović1, Harry Mönig2 and Rubén Pérez1,3

1Depto. Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid (UAM), 28049, Madrid, Spain

2Physikalisches Institut, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany 3Condensed Matter Physics Center (IFIMAC), UAM, 28049, Madrid, Spain

Metal oxides have many diverse technological applications in fields ranging from catalysis to electronics. Scanning probe microscopies have proven their extraordinary capacity in characterizing the surface properties that govern the chemical and electrical response of metal oxides at the atomic scale. Here we present a combined experimental and theoretical study on the Cu(110)-(2x1)O surface [1,2], where the oxide features added rows of alternate copper and oxygen atoms atop the metal surface (Fig. 1A). Atomic force microscopy (AFM) images of the metal oxide showed stripes with bright and dark spots (Fig. 1B) but it was not possible to distinguish between species in the added row. Following our previous study for the Cu(100)-(2x1)O system [3], we have used Density functional theory (DFT) calculations for the tip-sample interaction in order to understand the observed contrast and identify the main image features. These calculations have been performed with two metal Cu tips with different apex terminations: a Cu or an O atom. While the tip reactivity and the corresponding forces are


quite different for each tip termination, (Fig. 1C), we can conclude that maxima in the AFM images correspond to copper atoms in the added row.

Fig. 1. (A) Side an top view of metal-only (left) and metal oxide (right) of Cu(110)-(2x1)O surface [2]. (B) AFM image showing metal oxide domain (left) and metal-only domain (right). (C) Theoretical force vs distance spectroscopy curves obtained from the DFT simulations.

[1]. G. Prévot et al., Surf. Sci. 549 52-66 (2004). [2]. J. Bamidele et al,. Phys. Rev. B 86, 155422 (2012). [3]. M. Z. Baykara, et al., Phys. Rev. B 87, 155414 (2013).

P55

Curved Crystals: A different approach to Surface Science

J. E. Ortega1,2,3,4, R. González-Moreno1, F. López-Geijo1, Z. M. Abd-el-Fattah2, J. Lobo-Checa3, M. Corso2, U. Aseguinolaza2, A. Mugarza5, A. L. Walter4, A. Magaña2, M. Ilyin3,

L.A. Miccio4, M. Abadía2, and F. Schiller1,3

1BIHURCRYSTAL S.L., San Sebastian 2Departamento de Física Aplicada I, Universidad del País Vasco UPV/EHU, San Sebastian

3Centro de Física de Materiales, Centro Mixto CSIC-UPV/EHU, San Sebastian

4Donostia International Physics Center DIPC, San Sebastian 5Catalan Institute of Nanotechnology (ICN) Barcelona, Spain

Atomic steps strongly influence many physical-chemical phenomena that occur at surfaces, such as growth, chemical reactions, and electron scattering. It is therefore desirable to investigate the role of steps through the accurate control of the step density that can be achieved with a curved surface. We are capable of fabricating curved surfaces of different materials with a smooth variation of the crystal orientation (miscut angle) with respect to a high symmetry plane. Sample shapes and dimensions allow easy processing in vacuum, and are ideal for the exploration of step-dependent properties through scanning probe techniques, including 100-micron-size light beams.

It will be shown the powerful analytical capabilities of the curved surface approach, their advantages with respect to flat surfaces, as well as the new physics that arises by studying curved crystals: the complexity of the surface state scattering at step arrays of noble metals

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[1], the interplay of steps and dislocation networks to define exotic 2D lattices and band structures, the periodic texturing of quantum well states in ultrathin stepped metallic films [2], the smooth variation of surface core-level shifts in transition metals and overlayers, and the templated growth of nanostructures, e.g., metallic nanodots on curved oxide surfaces and low-dimensional ferromagnets with exotic magnetic anisotropy tuned on curved W and Pd.

[1]. M. Corso, F. Schiller, L. Fernández, J. Cordón, and J. E. Ortega, J. Phys.: Cond. Matter 21, 353001 (2009); J. E. Ortega, M. Corso, Z. M. Abd-el-Fattah, E. A. Goiri, and F. Schiller Phys. Rev. B 83, 085411 (2011); J. E. Ortega, J. Lobo-Checa, G. Peschel, S. Schirone, Z. M. Abd-el-Fattah, M. Matena, F. Schiller, P. Borghetti, P. Gambardella, and A. Mugarza, Phys. Rev. B 87, 115425 (2013).

[2]. F. Schiller at al. (submitted to N. J. of Physics).

P56

Characterization Of Mn0.006NbSe2 From Bulk To Few Layers

Alexandre Correa orellana1, Carmen Munuera1, Roberto Fabián Luccas1, Mar García Hernández1, Hermann Suderow2, Federico Mompean1

1 Instituto de Ciencia de Materiales de Madrid

2 Universidad Autónoma de Madrid

Transition metal dichalcogenides (TMDs) have already shown significant applications in various fields of optics, electrochemistry, electronics and sensors. In recent years, after the discovery of graphene, they have regained research interest due to their layered form that allows their exfoliation into small thicknesses containing mono- or multiple layers. Interesting thickness-dependent properties in these systems have been theoretically predicted, such as the realization of anomalous superconducting states when reaching the single layer. In addition, the intercalation of metals atoms between the van der Wals planes in TMDs is a particularly appealing approach to modify their physical properties, such as the charge density waves (CDW) and superconducting states [1,2,3]

In this work we have focused on the characterization of intercalated NbSe2 (Mn0.006NbSe2) in bulk and on its exfoliation down to few layers. 2H-NbSe2 present a charge density wave (TCDW=35K) and superconducting (TC=7.2K) states that are modified upon exfoliation [4]. Bulk Mn0.006NbSe2 shows structural differences when compared to the pure system as confirmed by X-ray diffraction data. In addition, we obtain a superconducting critical temperature of 6K (1.2K lower than in the NbSe2 pure material). Recently we have succeeded in the exfoliation of this material down to few layers flakes with the scotch tape method. Atomic Force Microscopy (AFM) and Raman spectroscopy have been used for the characterization of these flakes.

[1]. I. Naik, AIP Conf. Proc. 1349 (2011) 883 [2]. L.J. Li et al., J. Magn. Magn. Mater. 323 (2011) 2536 [3]. V.I. Maksimov et al., J. Alloy Comp. 384(2004) 33 [4]. N. E. Staley et al., Phys. Rev. B 80 (2009) 184505


P57

A digital electronics for fast SPM

Ignacio Horcas1,2, A. Gimeno1, P. Ares1,2, J. Gómez-Herrero2

1 Nanotec Electronica

2 Universidad Autónoma de Madrid

In this work, we present a new electronics for fast SPM control. The design is based on the combination of a state of the art Digital Signal Processor (DSP) board (TMDSEVM6678) and a Field Programmable Gate Array (FPGA) board that controls 16x16 bits resolution DACs plus 16x16 bit resolution ADCs. Using this new set up we are able to obtain acquisition rates as high as 1 frame/s (128x128 points) in standard calibration grids.


List of Participants

Last Name and Family Name Email Address

1 ABAD LOPEZ JOSE [email protected]

2 ABADIA MIKEL [email protected]

3 ABALLE LUCIA [email protected]

4 AGUSTINA ASENJO [email protected]

5 ALMONTE GARCIA LISA [email protected]

6 AMENABAR ALTUNA IBAN [email protected]

7 ANADON ALBERTO

8 ARES PABLO [email protected]

9 ARNAU ANDRES [email protected]

10 ARNAUDAS JOSE IGNANCIO [email protected]

11 AZPEITIA JON [email protected]

12 BARJA MARTINEZ SARA [email protected]

13 BARO VIDAL ARTURO [email protected]

14 BERGANZA EGUIARTE EIDER [email protected]

15 BERGER JAN [email protected]

16 BRIHUEGA IVAN [email protected]

17 CARBONELL SANROMA EDUARD [email protected]

18 CARRASCO PULIDO CAROLINA [email protected]

19 CIRIA MIGUEL [email protected]

20 COFFEY BLANCO DAVID [email protected]

21 COLCHERO PAETZ JAIME [email protected]

22 CORREA ARISTIZABAL ALEXANDER [email protected]

23 CORREA ORELLANA ALEXANDRE [email protected]

24 CORSO MARTINA [email protected]

25 DAZA RAFAEL [email protected]


26 DE LA TORRE CERDEÑO BRUNO [email protected]

27 DE OTEYZA DIMAS [email protected]

28 DE PABLO PEDRO [email protected]

29 DELGADO FERNANDO [email protected]

30 DIEZ FERRER JOSE LUIS [email protected]

31 DOMINGO MARIMON NEUS [email protected]

32 ELETA LOPEZ AITZIBER [email protected]

33 ELLNER MICHAEL [email protected]

34 ENGELUND MADS [email protected]

35 FAROKH PAYAM AMIR [email protected]

36 FERNANDEZ GOMEZ-RECUERO LAURA [email protected]

37 FERNANDEZ TORRENTE ISABEL [email protected]

38 FRANKE KATHARINA [email protected]

39 FUENTES PEREZ MARIA EUGENIA [email protected]

40 GARCIA ARRIBAS ARITZ [email protected]

41 GARCIA MARTIN JOSE MIGUEL [email protected]

42 GARCIA-LEKUE ARAN [email protected]

43 GASTALDO MICHELE [email protected]

44 GERBER CHRISTOPH [email protected]

45 GOMEZ MOÑIVAS SACHA [email protected]

46 GOMEZ RODRIGUEZ JOSE MARIA [email protected]

47 GOMEZ-HERRERO JULIO [email protected]

48 GONZALEZ HERRERO HECTOR [email protected]

49 GONZALEZ MARTINEZ JUAN FRANCISCO [email protected]

50 GONZALEZ MORENO RUBEN [email protected]

51 GOVYADINOV ALEXANDER [email protected]

52 HEINRICH BENJAMIN [email protected]


53 HERNANDEZ-RODRIGUEZ IRENE [email protected]

54 HERNANDO MERCEDES [email protected]

55 HORCAS IGNACIO [email protected]

56 JAAFAR RUIZ-CASTELLANOS MIRIAM [email protected]

57 JELINEK PAVEL [email protected]

58 JÖRG SCHÖNFELDER [email protected]

59 KAIDATZIS ANDREAS [email protected]

60 KRETZ BERNHARD [email protected]

61 LLAURO PORTELL AIDA [email protected]

62 LOBO-CHECA JORGE [email protected]

63 LOPEZ FAGUNDEZ MARIA FRANCISCA [email protected]

64 LOPEZ FRANCISCO [email protected]

65 LOPEZ MIR LAURA [email protected]

66 LOPEZ-POLIN GUILLERMO [email protected]

67 MAGALI PHANER GOUTORBE [email protected]

68 MAGAÑA VICANDI ANA [email protected]

69 MAJZIK ZSOLT [email protected]

70 MARCO ALEX [email protected]

71 MARTIN GAGO JOSE ANGEL [email protected]

72 MARTINEZ JIMENEZ DANIEL [email protected]

73 MARTIN RECIO ANA [email protected]

74 MARTINEZ BLANCO JESUS [email protected]

75 MARTINEZ CASTRO JOSE [email protected]

76 MARTINEZ RUIZ JOSE IGNACIO [email protected]

77 MARTINEZ VELARTE MARI CARMEN [email protected]

78 MENDEZ PEREZ CAMARERO JAVIER [email protected]

79 MERINO PABLO [email protected]


80 MICCIO LUIS ALEJANDRO [email protected]

81 MORENO HERRERO FERNANDO [email protected]

82 MORENO SIERRA CESAR [email protected]

83 MORENO UGEDA MIGUEL [email protected]

84 MORO LAGARES MARIA [email protected]

85 MORQUILLAS AZPIAZU NIEVES [email protected]

86 MUGARZA AITOR [email protected]

87 MUNUERA LOPEZ CARMEN [email protected]

88 NAVARRO PAREDES VIOLETA [email protected]

89 ORMAZA-SAEZMIERA MAIDER [email protected]

90 ORTEGA ENRIQUE [email protected]

91 ORTEGA ESTEBAN ALVARO [email protected]

92 OTERO MARTIN ROBERTO [email protected]

93 PALACIO RODRIGUEZ IRENE [email protected]

94 PALACIOS LIDON ELISA [email protected]

95 PASCUAL IGNACIO [email protected]

96 PEÑA GIL DIEGO [email protected]

97 PEREZ PERRINO ALMA EVA [email protected]

98 PEREZ RODRIGUEZ ANA [email protected]

99 PEREZ RUBEN [email protected]

100 PIANTEK MARTEN [email protected]

101 POU PABLO [email protected]

102 ARVIND RAMAN [email protected]

103 REIFENBERGER RONALD [email protected]

104 RODRIGO INSAUSTI LUCIA [email protected]

105 RODRIGUEZ HERMOSO DIEGO [email protected]

106 ROGERO CELIA [email protected]


107 ROMERO MUNIZ CARLOS [email protected]

108 RUBIO VERDU CARMEN [email protected]

109 SALGADO GARCES CARLOS EDUARDO [email protected]

110 SANCHEZ LACASA JESUS [email protected]

111 SANCHEZ PORTAL DANIEL [email protected]

112 SANCHEZ SANCHEZ CARLOS [email protected]

113 SARASOLA IÑIGUEZ ANE [email protected]

114 SCHIRONE STEFANO [email protected]

115 SERRATE DONOSO DAVID [email protected]

116 SIMIC-MILOSEVIC VIOLETA [email protected]

117 THOMSON NEIL [email protected]

118 URDAMPILLETA MARTA [email protected]

119 VERDAGUER ALBERT [email protected]

120 VILHENA GUILHERME [email protected]

121 VITALI LUCIA [email protected]

122 ZOTTI LINDA ANGELA [email protected]

9:00W

elcome w

ords

9:159:15

10:00David Coffey

10:00M

agali Phaner10:15

10:20Fernando Delgado

10:20Alm

a Eva10:40

Pablo Ares10:40

Alvaro Ortega

11:00Jesús M

artínez11:00

Gilherme Vilhena

11:00Dim

as de Oteyza

11:20M

aría Moro

11:20Iban Am

enabar11:20

Amir Farokh

11:40CO

FFEE BREAK 11:40

COFFEE BREAK

11:40CO

FFEE BREAK

12:00Carlos Sanchez

12:00Aran García

12:00Cesar M

oreno12:20

Roberto Otero

12:20Ana M

artín12:20

Albert Verdaguer12:40

José I. Martínez

12:40Guillerm

o Lopez12:40

Miriam

Jaafar13:00

Maider O

rmaza

13:00N

eus Domingo

13:00Poster Prizes

13:2013:20

LUN

CH13:20

Final remarks

14:30O

rganizing Comm

ittee Meeting

15:30Stefano Schirone

15:30Violeta N

avarro15:50

Héctor González15:50

Elisa Palacios16:10

Pablo Merino

16:10Alejandro M

iccio16:30

Miguel M

oreno16:30

COFFEE BREAK

16:50Cárm

en Rubio16:50

Carolina Carrasco17:10

COFFEE BREAK

17:10Lucía Aballe

Session Tribute to Prof. A. Baró17:30

Alexander Govyadinov17:30

Welcom

e words

17:35Christoph G

erber17:50

POSTER SESSIO

N18:05

Ron Reifenberger18:35

Arvind Raman

19:05Ignacio Pascual

20:00Free tim

e20:30

Bus to conference dinner

WEDN

ESDAY 27THRU

SDAY 28FRIDAY 29

Session 3. Graphene and 2D-system

s ISession 6. N

ew developm

ents & related techniques

Session 7. Combined AFM

/STM I

Session 1. Magnetism

Session 2. Syntesis on SurfacesSession 5. G

raphene and 2D-systems II

Session 4. AFM applications in biology

Katharina FrankeN

eil H.Thomson

LUN

CH

Pavel Jelinek

Session 8. Combined AFM

/STM II

Fuerzas y Túnel 2014 - mscnano.eu€¦ · Centro de Física de ... (UAM) Jose Ignacio Pascual...

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