Dresden 2011 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 99: Electron and spin dynamics II
O 99.6: Vortrag
Freitag, 18. März 2011, 12:30–12:45, WIL B321
Phonon-mediated adsorption and desorption of an image bound electron — •Rafael Leslie Heinisch, Franz Xaver Bronold, and Holger Fehske — Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald, Deutschland
We study phonon-mediated physisorption, that is, temporary trapping and desorption, of an electron in polarization-induced external surface states (image states) of a dielectric surface [1,2]. Electron energy relaxation at the surface is enabled by surface vibrations whose energy scale is the Debye energy. Due to the large depth of the surface potential with respect to the Debye energy, multiphonon processes are important. Using a quantum kinetic rate equation for the occupancy of the image states, we calculate desorption times and prompt as well as kinetic sticking coefficients for an electron at a dielectric surface. 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 for graphite, MgO, CaO, Al2O3 and SiO2.
[1] R. L. Heinisch et al., Phys. Rev. B 81, 155420 (2010)
[2] R. L. Heinisch et al., Phys. Rev. B 82, 125408 (2010)