title: Force dependence of transition rates in atomic friction.
abstract: The lateral forces during stick-slip motion of an atomic force microscope cantilever on highly oriented pyrolytic graphite are measured and analyzed. We identify the regimes where thermally activated interstitial hopping of the cantilever tip proceeds according to a single-step reaction scheme and extract the corresponding force-dependent transition rates directly from the experimental data. We find that such a single-step reaction scenario is valid only at relatively high velocities, while at slower pulling speeds, a more complicated hopping mechanism must be at work. We suggest formation of multiple bonds of the tip-sample contact as a possible candidate for this mechanism.
authors.affiliation: Universität Bielefeld, Fakultät für Physik, 33615 Bielefeld, Germany.
authors.forename: Mykhaylo
authors.initials: M
authors.lastname: Evstigneev
authors.forename: André
authors.initials: A
authors.lastname: Schirmeisen
authors.forename: Lars
authors.initials: L
authors.lastname: Jansen
authors.forename: Harald
authors.initials: H
authors.lastname: Fuchs
authors.forename: Peter
authors.initials: P
authors.lastname: Reimann