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Berlin 2008 – scientific programme

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O: Fachverband Oberflächenphysik

O 36: Surfaces and Films: Forces, Structure and Manipulation

O 36.9: Talk

Tuesday, February 26, 2008, 16:15–16:30, MA 041

Variations of the electrochemical potential at monoatomic steps resolved by scanning tunneling potentiometry — •Mark Kaspers1, Alexander Bernhart1, Bastian Weyers1, Evgeny Zubkov1, Rolf Möller1, Christian Bobisch2, Jan Homoth3, Martin Wenderoth3, Thomas Druga3, Lars Winking3, and Rainer-G. Ulbrich31University of Duisburg-Essen, Department of Physics, Duisburg, Germany — 2University of California, Irvine, USA — 3Georg-August-University, Physical Institute, Göttingen, Germany

On macroscopic scale the energy dissipation of electrons scattering at phonons, atomic steps, grain boundaries etc. contribute to the total resistivity. To gain access to these effects on the nanoscale scanning tunneling potentiometry was performed on a Si(111)-(√3×√3)-Ag surface superstructure. The experimental data show how the variations of the electrochemical potential are correlated to the topography. E.g. the potential drops at step edges on a lengthscale of about 1.2nm.

Our setup consists of an optimized Omicron Nanoprobe equipped with three independent STM-units. Two STM-tips were used to apply a constant lateral current through the Ag adlayer. The third tip maps the topography as well as the local potential simultaneously.

Our experiment gives access to the spatial variations of the potential inside the structure itself right across the obstacles. This provides a new insight in the elementary processes of the electric resistance observed in macroscopic experiments.

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