Mechanism of high-resolution STM/AFM imaging with functionalized tips

Prokop Hapala, Georgy Kichin, Christian Wagner, F. Stefan Tautz, Ruslan Temirov, and Pavel Jelínek
Phys. Rev. B 90, 085421 – Published 19 August 2014
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Abstract

High-resolution atomic force microscopy (AFM) and scanning tunneling microscopy (STM) imaging with functionalized tips is well established, but a detailed understanding of the imaging mechanism is still missing. We present a numerical STM/AFM model, which takes into account the relaxation of the probe due to the tip-sample interaction. We demonstrate that the model is able to reproduce very well not only the experimental intra- and intermolecular contrasts, but also their evolution upon tip approach. At close distances, the simulations unveil a significant probe particle relaxation towards local minima of the interaction potential. This effect is responsible for the sharp submolecular resolution observed in AFM/STM experiments. In addition, we demonstrate that sharp apparent intermolecular bonds should not be interpreted as true hydrogen bonds, in the sense of representing areas of increased electron density. Instead, they represent the ridge between two minima of the potential energy landscape due to neighboring atoms.

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  • Received 16 June 2014
  • Revised 23 July 2014

DOI:https://doi.org/10.1103/PhysRevB.90.085421

©2014 American Physical Society

Authors & Affiliations

Prokop Hapala*

  • Institute of Physics, Academy of Sciences of the Czech Republic, v.v.i., Cukrovarnická 10, 162 00 Prague, Czech Republic

Georgy Kichin, Christian Wagner, F. Stefan Tautz, and Ruslan Temirov

  • Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany and Jülich Aachen Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany

Pavel Jelínek

  • Institute of Physics, Academy of Sciences of the Czech Republic, v.v.i., Cukrovarnická 10, 162 00 Prague, Czech Republic and Graduate School of Engineering, Osaka University 2-1, Yamada-Oka, Suita, Osaka 565-0871, Japan

  • *Corresponding author: hapala@fzu.cz
  • r.temirov@fz-juelich.de
  • pavel.jelinek@fzu.cz

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Issue

Vol. 90, Iss. 8 — 15 August 2014

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