Regensburg 2013 – scientific programme
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O: Fachverband Oberflächenphysik
O 9: Nanotribology
O 9.10: Talk
Monday, March 11, 2013, 12:45–13:00, H42
Measuring the directionality of a chemical bond with lateral force microscopy — •Daniel Meuer1, Alfred J. Weymouth1, Pingo Mutombo2, Martin Ondráček2, Thorsten Wutscher1, Pavel Jelinek2, and Franz J. Giessibl1 — 1University of Regensburg, Regensburg, 93053, Germany — 2Institute of Physics of Czech Academy of Science, Prague, CZ-162 53, Czech Republic
Lateral forces control friction [1] and diffusion processes of adsorbates on a surface [2]. Lateral forces can be extracted from 3D normal force measurements [3]. In this contribution we show a direct lateral force measurement by dynamic lateral force microscopy (LFM). In the past LFM has made great advances with smaller oscillations, presenting atomic-scale observations on Si(111)-7x7 [4] and graphite [5]. We resolve lateral bond stiffnesses in a sample that is expected to show a strong azimutal dependence of lateral stiffnesses: the hydrogenated Si(100) surface. The "rocking horse"-type Si dimers change their orientations by 90° over a single atomic step, correspondingly, the experiment shows clearly a significant difference between the two directions. Furthermore the DFT-based calculations indicate that the tip oscillation induces a significant out-of-plane motion of the Si dimer.
[1] F.J. Giessibl et al, Proc. Nat. Acad. Sci. 99, 12006 (2002).
[2] T. Sonnleitner, et al, Phys. Rev. Lett. 107, 186103 (2011).
[3] M. Ternes, et al, Science 319, 1066 (2008)
[4] S. Kawai et al, Phys. Rev. B 79, 195412 (2009).
[5] S. Kawai et al, Phys. Rev. B 81, 085420 (2010).