Regensburg 2004 – scientific programme
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O: Oberflächenphysik
O 31: Oberflächenreaktionen II
O 31.2: Talk
Thursday, March 11, 2004, 11:30–11:45, H36
Interaction of He, Ne and Ar metastable atom beams with multilayer tunnel systems — •Domokos Kovacs1, Johannes Berndt1, Jörg Winter1, and Detlef Diesing2 — 1Experimentalphysik 2, Ruhr-Universität Bochum — 2Institut für Schichten und Grenzflächen 3, Forschungszentrum Jülich
The collision of metastable rare gas atoms He, Ne and Ar with a metal surface is a well investigated process in surface science. The process leads with an efficient rate to a relaxation of the atoms and a simultaneous electron emission from the metal surface. The energy spectrum of the emitted electrons is a wide distribution with a maximal energy of 4 eV. Due to the significant width of the emitted electron spectrum one can think about a distribution of excited defect electrons in the electron emitting metal surface. This kind of electronic excitation is difficult to detect in a bulk metal. In a 15 nm thick silver film however the defect electrons may reach the opposite interface of the metal film. In a multilayer tunnel system, separating the thin silver film from an aluminium film by a 2 nm thick oxide spacer one can detect an electron current from the base electrode to the silver electrode which is exposed to the metastable beam. Competing processes with deexcitation are discussed. By the application of a grid filter in the transport tube between the discharge and the vacuum chamber one can seperate between ion neutralization reactions and metastable deexcitation. By an asymmetric chopping unit which allows the exposition of the samples to alternating particle-photon and photon fluxes we discuss the contribution of the photon induced tunnel current to the total tunnel current.