Berlin 2005 – scientific programme

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DY: Dynamik und Statistische Physik

DY 51: Einstein Symposium Brownian Motion, Diffusion and Beyond (SYBM) – Contributed Talks II

DY 51.1: Talk

Wednesday, March 9, 2005, 10:15–10:30, TU H2032

Rate theory of the stick-slip motion of an AFM tip in friction force microscopy experiments — •Mykhaylo Evstigneev and Peter Reimann — Universität Bielefeld, Universitätsstraße 25, 33615 Bielefeld

During the stick-slip motion of an AFM tip contacting with a uniformly moving atomically clean surface, the force developed in the cantilever spring performs random sawtooth-like oscillations resulting from the thermally activated transitions of the tip from one surface site to the next. Using escape rate theory, the probability distribution of forces is calculated numerically to deduce the time-average lateral force as a function of pulling velocity. A much simpler analytic transcendental equation for the average force is proposed and its approximate solution is obtained. The high accuracy of this analytic approximation is demonstrated via comparison with the numerical results. The analogous force-velocity relations existing in the literature are shown to be the limiting cases of low and high cantilever spring constants of our formula.