Münster 1997 – scientific programme
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CP: Chemische Physik
CP 16: Poster zur Sitzung CP6
CP 16.7: Poster
Tuesday, March 18, 1997, 18:30–21:15, FBH
Partially coherent excitation transfer in librationally moving bichromophoric molecules — •T. Pálszegi1, V. Szőcs2, and H.F. Kauffmann3 — 1Department of Chemical Physics, Faculty of Chemical Technology, Slovak Technical University, Radlinskeho 9, 812 37 Bratislava, Slovakia — 2Institute of Chemistry, Faculty of Natural Sciences, Comenius University, Mlynska dolina CH2, 84215 Bratislava, Slovakia — 3Institut für Physikalische Chemie der Universität Wien, Währingerstrasse 42, A-1090 Wien, Österreich
The influence of the librational motion on the coherence character of electronic excitation transfer in bichromophoric molecules has been investigated. The librational motion has been described by diffusion of the torsional angle of chromophores (randomly modulating the resonant coupling). The dissipative influence of fast vibrational degrees of freedom has been included by Haken-Strobl-Reineker γ parameters. The time evolution of the density matrix of a system of bichromophoric molecules has been calculated summing the solutions of the effective Liouville equation for many stochastic histories of the torsional angle. For different rates of librational diffusion and for different broadness of Gaussian torsional angle distributions the time evolution of electronic excitation of a model bichromophoric molecule has been studied. The slow time-scale fluctuations (relative to the characteristic time of excitation transfer) of torsional angles, representing spectral diffusion, are causing additional coherence decay (sup. by ÖAB OWP-142; FWF P11344).