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O: Fachverband Oberflächenphysik
O 35: Poster Session II (Polymeric biomolecular films; Nanostructures; Electronic structure; Spin-orbit interaction; Phase transitions; Surface chemical reactions; Heterogeneous catalysis; Particles and clusters; Surface magnetism; Electron and spin dynamics; Surface dynamics; Methods; Electronic structure theory; Functional molecules)
O 35.87: Poster
Dienstag, 27. März 2012, 18:15–21:45, Poster B
On the relation between fluctuations in STM currents and diffusion coefficients of molecules on surfaces — •Susanne Hahne1, Julian Ikonomov2, Moritz Sokolowski2, and Philipp Maass1 — 1Department of Physics, University of Osnabrück, Barbarastr. 7, 49076 Osnabrück, Germany — 2Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115 Bonn, Germany
A widely used method to measure surface diffusion coefficients is by tracking particles via STM, FEM or FIM. To obtain reliable data one needs a good statistic, which is generally quite extensive. Also these methods are limited to sufficiently small mobilities. An alternative experimental approach is the recording of the signal fluctuations in time from a locally fixed microscope [e.g. tunneling current in case of STM; frequency/height in case of AFM]. This procedure on the other hand needs a good theoretical description in order to obtain reliable results. Three different methods can be applied to analyze this signal fluctuations: (i) Determination of the autocorrelation-function or extraction of the peaks in the fluctuation, where either (ii) the distribution of peak widths is studied or (iii) the distribution of peak to peak distances. We critically discuss and extend analytical theories underlying these methods and evaluate their power by comparison to recent experiments [1].
[1] J. Ikonomov, P. Bach, R. Merkel, and M. Sokolowski, Phys. Rev. B 81, 161412(R) (2010).