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MO: Fachverband Molekülphysik

MO 22: Theorie: Quantenchemie und Moleküldynamik

MO 22.2: Poster

Thursday, March 13, 2008, 16:30–19:00, Poster C1

Damping of vibrational dynamics in dimers attached to He nanodroplets — •Martin Schlesinger and Walter Strunz — Theoretische Quantendynamik, Physikalisches Institut, Universität Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg

Femtosecond pump-probe spectroscopy is a well-established tool for studying vibrations in diatomic molecules [1]. Recent experiments investigate the evolution of vibrational wave packets excited in K₂ dimers attached to superfluid helium nanodroplets [2]. Deviations from gas-phase spectra are seen both in the time- and frequency domain. We simulate the pump-probe signal for the free molecule [3] and include different models to account for a possible damping of the wave packet due to the helium environment. For different damping constants, the effect is investigated by comparing with simulated gas-phase (no damping) and experimental spectra, for which we find good agreement. Our calculations show a shift of the central frequency of oscillations as also seen in the experiment.

[1] T. Baumert, V. Engel, C. Röttgermann, W. T. Strunz, and G. Gerber, Chem. Phys. Lett.  191, 639 (1992).

[2] P. Claas, G. Droppelmann, C. P. Schulz, M. Mudrich, and F. Stienkemeier, J. Phys. B: At. Mol. Opt. Phys. 39, 1151 (2006).

[3] R. de Vivie-Riedle, B. Reischl, S. Rutz, und E. Schreiber, J. Phys.  Chem. 99, 16829 (1995).