Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 88: Symposium Nanotribology
O 88.1: Hauptvortrag
Freitag, 26. März 2010, 10:15–10:45, H1
Atomic friction under ultrahigh vacuum conditions — •Ernst Meyer1, Enrico Gnecco1, Pascal Steiner1, Gregor Fessler1, Sascha Koch1, Thilo Glatzel1, Alexis Baratoff1, Mircin Kisiel1, Urs Gysin1, Akshata Rao1, Shigeki Kawai1, and Sabine Maier2 — 1Department of Physics, University of Basel, Switzerland — 2Lawrence Berkeley National Labs, USA
It will be shown that atomic-scale stick-slip is relatively well understood, where the dependence on velocity and normal force is experimentally investigated and interpreted in terms of an extended Tomlinson model. It is essential to include thermal actuation to understand the observed phenomena. The transition from atomic-scale stick slip to continuous sliding will be described. The detailed analysis yields the energy corrugation and the lateral contact stiffness as a function of load. Very low lateral contact stiffness values of the order a few N/m are found. Experiments will be shown to determine the normal contact stiffness, simultaneously. Slip distances are related to the atomic lattice, where mostly single but also multiple slips are observed. An important parameter is the damping coefficient of the contact, which can be estimated from histograms of slip distances. Friction can be reduced with rather high accuracy by electrostatic actuation. An essential prerequisite are the high intrinsic resonance frequencies of the nanometer-sized contacts, which gives the opportunity to move in nearly continuous way without instabilities. Therefore, average friction values become negligible and small objects can be moved without extremely small dissipation.