Hannover 2010 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 21: Poster: Plasma-Wall Interaction

P 21.2: Poster

Montag, 8. März 2010, 16:00–18:00, Lichthof

Phonon-mediated adsorption and desorption of electrons at surfaces — •Rafael Leslie Heinisch, Franz Xaver Bronold, and Holger Fehkse — Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald, Germany

Adsorption and desorption of charged particles on plasma boundaries are important processes, because they regulate the charge balance on the boundary and thereby also influence the properties of the bulk plasma. We present an exploratory calculation of the electronic desorption time and sticking coefficient from a kinetic rate equation for phonon-mediated physisorption at dielectric surfaces. Electrons can be temporarily bound to the surface in a polarisation-induced surface potential. Their energy relaxation at the surface is enabled by surface vibrations whose energy scale is the Debye energy. Depending on the depth of the surface potential with respect to the Debye energy, multi-phonon processes can be important for physisorption. We show that the classification of the potential depth and bound state level spacing in terms of Debye energies is paramount for a scenario of sticking and desorption and present results taking one and two phonon processes into account.