Düsseldorf 2007 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 24: Femtosecond Spectroscopy III
MO 24.6: Vortrag
Dienstag, 20. März 2007, 15:45–16:00, 6C
Model studies of laser induced femtosecond dynamics in the excited states of β-carotene — •Judith Voll, Benjamin Fingerhut, and Regina de Vivie-Riedle — LMU Department Chemie, Butenandt-Str. 11, 81377 München, Germany
Based on data from coherent control experiments performed on β-carotene in the group of M. Motzkus we present a model for the theoretical description of the laser induced quantum dynamics. After excitation by a femtosecond pulse from the electronic ground state into the S2 state the system relaxes via conical intersections and is then detected in the S1 state by transient raman spectroscopy.
To specify the kinetic hamiltonian, the raman modes involved, their force constants and the relative position of the interacting potentials were extracted from ab initio calculations. With this model the mechanism of internal conversion is studied, incorporating vibrational cooling in the S1 state. The influence of the topology of the electronic states as well as the position of the S2 - S1 conical intersection on the dynamics are examined. These results are used to investigate the controllability of the transfer rate by modulated laser pulses.