Dresden 2003 – wissenschaftliches Programm
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O: Oberflächenphysik
O 23: Oberfl
ächenreaktionen II
O 23.1: Vortrag
Dienstag, 25. März 2003, 15:00–15:15, M\"UL/ELCH
Spectroscopy of small electronic excitations (E < Evacuum) on gold surfaces during exposure to metastable noble gas and hydrogen radical beams — •Detlef Diesing1, Johannes Berndt2, and Jörg Winter2 — 1Institut für Schichten und Grenzflächen 3, Forschungszentrum Jülich — 2Anwendungsorientierte Plasmaphysik, Ruhr- Universität Bochum
The collision of metastable gas atoms with a metal surface is a well investigated process in surface science. The process leads with an efficient rate to a relaxation of the atom and a simultaneous electron emission from the metal surface. In general we can not expect that chemical relaxation reactions deposit so high energies which allows electrons to leave the metal. A challenging solution is the internal detection of electronic excitations on surfaces by thin film Schottky diodes or tunnel diodes. In the present work tunnel diodes are used to detect the electronic excitation of 20 nm thick gold films in argon, neon and hydrogen beams. The beams are produced by a surface wave sustained microwave discharge which contains radicals as well as ions and higly vibrationally excited diatomic molecules. By a chopping unit in the radical beam and a grid filter in the particle beam we could detect chopped tunnel currents, which clearly correlate with the plasma parameters as microwave power and gas flow density as well as with the potentials of the grid filter. By an application of a bias voltage the tunnel diode can be used as an internal spectrometer. The energy of hot defect electrons on the gold surface produced in a pulsed argon metastable beam can be determined to EF−E = 0.94 e V .