Berlin 2005 – wissenschaftliches Programm
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O: Oberflächenphysik
O 42: Oberfl
ächenreaktionen II
O 42.5: Vortrag
Dienstag, 8. März 2005, 11:45–12:00, TU EB407
Detection of low energy electronic excitations( E < Evacuum) during the interaction of metastable rare gas atoms with metal surfaces. — •Domokos Kovacs1, Johannes Berndt1, Jörg Winter1, and Detlef Diesing2 — 1Experimentalphysik 2, Ruhr-Universität Bochum — 2Institut für Schichten und Grenzflächen 3, Forschungszentrum Jülich
The interaction of metastable rare-gas atoms with a metal surface gives rise to deexcitation accompanied by electron emission. While the electron emission into the vacuum is well investigated, the low energy electronic excitations cannot be detected by classical spectroscopic methods. For their detection, a thin film tunnel junction was used. It consists of a silver film (15 nm) exposed to the metastable atom beam and of an aluminum film (30 nm), separated by a very thin (2-3 nm) aluminum-oxide layer. In such a multilayer system, low energy electronic excitations can be detected as a pulsed tunnel current in the base aluminum electrode by chopping the metastable atom beam. A bias induced reversible polarity change in the metastable induced tunnel current was observed. It depends strongly on the intrinsic properties of the metastable atoms (excitation energy), but does not depend on the intensity of the metastable atom beam. In order to explain the experimental data a theoretical model considering tunnel processes between a ground state electron gas and an excited free electron gas is proposed.