NCAFM2023 Programme Booklet

Monday 1400 - 1420

THE NATURE OF A CHEMICAL BOND INFLUENCES SLIDING FRICTION AT THE ATOMIC SCALE

Alfred J. Weymouth 1 , O. Gretz 1 , S. Nam 1 , L. Hörmann 2 , O.T. Hofmann 2 , F.J. Giessibl 1

1 Faculty of Physics, University of Regensburg; Regensburg, 93053, Germany 2 Institute of Solid State Physics, Graz University of Technology; Graz, 8010, Austria.

Email: jay.weymouth@ur.de

We perform lateral force microscopy (LFM), a technique in which the AFM sensor is mounted so that the tip oscillates laterally over a surface [1]. Using techniques established in FM-AFM, we can evaluate both the conservative and dissipative interactions with the surface. We can also functionalize our tip with a single CO molecule for a well-defined and inert tip termination [2]. Previously, we discovered that we could directly measure the energy loss as we pull our tip – an asperity ending in a well-controlled single atom – over a single chemical bond [3,4]. In this contribution, we address the question of whether the nature of the chemical bond has a direct impact on sliding friction. We find that friction is indeed higher over a covalent bond compared to a hydrogen bond.

Fig. a) The frequency shift, f, is a measure of the conservative force interaction and allows us to determine the position of each surface atom. b) The energy loss is higher over chemical bonds that are perpendicular to the direction of the tip oscillation (horizontal). c) We interpret this energy loss as being a result of the flexible apex snapping over a chemical bond.

References [1] F. J. Giessibl, M. Herz, and J. Mannhart, Proc. Natl. Acad. Sci., 2002, 99, 12006. [2] L. Gross, F. Mohn, N. Moll, P. Liljeroth, and G. Meyer, Science, 2009, 325, 1110. [3] A. J. Weymouth, E. Riegel, O. Gretz, and F. J. Giessibl, Phys. Rev. Lett., 2020, 124, 196101. [4] A. J. Weymouth, O. Gretz, E. Riegel, and F. J. Giessibl, Jpn. J. Appl. Phys., 2022, 61, SL0801.

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