Regensburg 2013 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 78: Surface Dynamics I

O 78.4: Vortrag

Donnerstag, 14. März 2013, 16:45–17:00, H42

Surrogate Hamiltonian study of laser induced desorption of CO/NiO(100) and CO/TiO₂(110) — Erik Asplund and •Thorsten Klüner — Institut für Reine und Angewandte Chemie, Carl von Ossietzky Universität Oldenburg, Germany

In this study, microscopic models for electronic relaxation in femtosecond laser induced desorption experiments are presented. The surfaces in desorption experiments constitute environments for the molecules studied. Due to interactions between an adsorbed molecule and the surface, energy and phase exchange emerge. The photodesorption process consists of three steps: first the adsorbed molecule is excited by an external laser field, thereafter the relaxation process transfers energy to the surface and finally desorption. A theoretical investigation of laser induced desorption must hence treat all involved process, i.e. excitation, excited state dynamics and relaxation, on equal footing. This can be realized within the Surrogate Hamiltonian approach [1]. Furthermore, the Surrogate Hamiltonian method enables a microscopic description of excitation and relaxation process for open quantum systems. The Surrogate Hamiltonian approach is applied to electronic relaxation of CO adsorbed on NiO(100) and TiO₂(110). Ab initio electronic potential energy surfaces are combined with microscopic descriptions of the interactions between the adsorbed molecule with the surfaces in order to gain insight in the desorption mechanism. Furthermore, life times, desorption probabilities, and velocity distributions for the desorbing molecules are presented.

[1] R. Baer, and R. Kosloff, J. Chem. Phys. 106, 8862 (1997).