Berlin 2005 – wissenschaftliches Programm

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O: Oberflächenphysik

O 42: Oberfl
ächenreaktionen II

O 42.3: Vortrag

Dienstag, 8. März 2005, 11:15–11:30, TU EB407

The adsorption of gold on gold surfaces – where does the binding energy go ? — •Michael Kayser¹, Eckart Hasselbrink¹, and Detlef Diesing² — ¹Institute of Physical and Theoretical Chemistry, University of Duisburg-Essen, Campus Essen — ²Institut für Schichten und Grenzflächen 3, Forschungszentrum Jülich

The chemistry and physics of the deposition of a metal atoms on a metal surface is not only interesting for the understanding of fundamental processes like charge transfer, chemical bonding and energy dissipation but also for altering or even tailoring properties and behaviour of surfaces [1] for their industrial application. The deposition of a metal atom on a metal surface leads to the release of the heat of sublimation which is completely transferred to the substrate. The question to be answered is to which extend the binding energy is transferred to the electronic system and to the phononic system of the gold. Electronic excitations within their short lifetime of several tens of fs [2] can be detected using a tunnel junction realized by a metal-insulator-metal system. We present measurements which prove that the binding energy is at least partly transferred to the electronic system of the gold substrate. The adsorption induced electronic excitation is measured as a tunnel current at 0 V bias voltage across the tunnelling barrier. The observed tunnel current is directly proportional to the gold atom flux. Additional processes as photo induced tunnelling play a minor role in the experiment.
M. Ø. Pedersen, S. Helveg, A. Ruban - Surf. Sci. 426 (1999) 395 - 409 [2] S. Meyer et al., Phys. Rev. Lett. 93, 137601 (2004)