Dresden 2006 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
O: Oberflächenphysik
O 29: Poster session II (Nanostructures, Magnetism, Particles and clusters, Scanning probe techniques, Time-resolved spectroscopy, Structure and dynamics, Semiconductor surfaces and interfaces, Oxides and insulators, Solid-liquid interfaces)
O 29.43: Poster
Mittwoch, 29. März 2006, 14:30–17:30, P2
Dynamic Force Microscopy - Manifestations of Rare Atomic Jumps: Experiment and Simulation — •B. Ittermann1, R. Hoffmann1, A. Baratoff2, L. Kantorovich3, T. Trevethan3, and H. v. Löhneysen1,4 — 1Physikalisches Institut and DFG-Center for Functional Nanostructures (CFN), Universität Karlsruhe, D-76128 Karlsruhe — 2NCCR on Nanoscale Science, Institute of Physics, University of Basel — 3Department of Physics, Kings College London — 4Institut für Festkörperphysik, Forschungszentrum Karlsruhe, D-76021 Karlsruhe
In recent non-contact scanning force microscopy experiments, jumps of the resonance frequency shift were observed below a critical tip-sample distance above specific atomic sites on a KBr (001) surface [1]. At the same distance additional energy dissipation related to the jumps sets in. The two branches of the frequency vs. distance curves between which the jumps occur are interpreted as the interaction of the surface with the tip being in two different configurational states. We proposed a model of the tip where an atom can hop from position A to position B in a double well potential. This proposal is checked with atomistic simulations for a small KBr cluster representing the tip and a KBr slab with a planar surface as sample [2]. The force as a function of distance obtained from the simulations is compatible with a double minimum potential for the different states A and B of the tip. Molecular dynamics simulations are planned in order to study the process at finite temperatures. [1] R. Hoffmann et al., to be published [2] R. Hoffmann et al., Phys. Rev. Lett. 92, 146103 (2004)