München 2004 – scientific programme

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MO: Molekülphysik

MO 7: Femtosekundenspektroskopie: Protontransfer + Energiefluss

MO 7.4: Talk

Monday, March 22, 2004, 14:45–15:00, HS 315

Laser Driven Proton Motion in a Hydrogen-bonded System. A Quantum Molecular Dynamics Approach — •Milena Petković — Institut für Chemie, Physikalische und Theoretische Chemie, Freie Universität Berlin, Takustr. 3, 14195 Berlin

M. Petković, O. Kühn

Hydrogen bond dynamics in Salicylaldimine after an excitation of the OH bending/stretching vibration with an ultrafast IR laser pulse is studied, using a 7-dimensional CRS [1] model comprising the large amplitude H-atom motion and five normal modes of the molecular scaffold. The numerical solution of the time-dependent Schrödinger equation was performed employing the MCTDH approach [2]. Bending vibration: besides the bending vibration the fundamental transition of highest frequency scaffold mode is appreciably excited, so the dynamics is characterized by a coherent wave packet motion. The remaining normal modes have also been excited, but to a much lower extent. Stretching vibration: all modes were noticably excited. Strong couplings lead to fast subpicosecond IVR processes. During the pulse, most of the energy flows into the reaction coordinates, but after the pulse has been turned off, the ehergy was redistributed among all normal modes. The OD bending/stretching vibration of the deuterated species has also been excited and a pronounced isotope effect on the intramolecular energy flow was observed.

[1] B. A. Ruf; W. H. Miller, J. Chem. Soc. Faraday Trans. 2, 1988, 84, 1523

[2] M. H. Beck, A. Jäckle, G. A. Worth; H.-D. Meyer, Phys. Reports, 2000, 324, 1