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O: Fachverband Oberflächenphysik

O 52: Time-Resolved Spectroscopy III

O 52.13: Vortrag

Mittwoch, 27. Februar 2008, 18:15–18:30, MA 042

Enhanced photodesorption by vibrational pre-excitation: Quantum model simulations for Cs/Cu(111) — •Dominik Kröner — Universität Potsdam, Institut für Chemie, Theoretische Chemie, Karl-Liebknecht-Str. 24-25, D-14476 Potsdam, Germany

  We present electronic and nuclear quantum model simulations for the direct, laser-induced charge transfer from a Cu(111) surface state, to an unoccupied resonance state of an adsorbed Cs-atom. An one-electron model potential for Cu(111) by Chulkov et al. [1] is extended by a Cs adsorbate potential to determine energies and lifetimes of electronic states of Cs/Cu(111) at low coverage. In addition, empirical nuclear potential energy surfaces of the electronic ground and the antibonding excited state along the Cs-Cu distance are constructed. For both models, electronic and nuclear, we perform open-system quantum dynamics with the goals: (i) to estimate the excitation (charge transfer) and Cs desorption probabilities [2], (ii) to optimize the charge transfer process by laser pulse shaping using optimal control theory [2], and (iii) to increase the negligible desorption yield of Cs from the Cu surface, obtained from direct UV excitation, by vibrationally pre-exciting the Cs-Cu bond using a THz-laser pulse [3].

[1] E. V. Chulkov, V. M. Silkin, P. M. Echenique, Surf. Sci. 437, 330 (1999).

[2] D. Kröner, T. Klamroth, M. Nest, P. Saalfrank, Appl. Phys. A 88, 535 (2007).

[3] D. Kröner, S. Klinkusch, T. Klamroth, Surf. Sci., accepted (2007).