Heidelberg 1999 – scientific programme
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Q: Quantenoptik
Q 26: Poster: Laserspektroskopie
Q 26.10: Poster
Tuesday, March 16, 1999, 16:30–18:30, PH
Fluorescence Fluctuation Interferometry in Model Molecular Structures — •V. Szőcs1, T. Pálszegi2, and H.F. Kauffmann3 — 1Inst. Chemistry, Comenius Univ., Mlyn.dol. CH2, 842 15 Bratislava, Slovakia — 2Dpt.Chem. Phys.,Sl. Tech. Univ., Radlinského 9, 812 37 Bratislava, Slovakia — 3Inst. f. Phys. Chem., Univ. Wien, Waehringerstr.42, 1090 Wien, Austria
Fluctuations of correlated fluorescence of a (molecular) system driven by a pair of time-delayed, phase-randomized pulses (dipole-coupled, semiclassical electric field) allow direct insight into internal dynamics, energy level splittings, and coherence relaxation of molecules in condensed phases. By using a discrete-level model we clarify the effect of IHLB and phonon coupling on molecules embedded in a solid matrix, in accordance with recent experimental results [1]. The time-domain study on inter-molecular transfer and phonon dynamics is accomplished for a two-site model of a bichromophoric molecule in a generalization of recent work [2] where a nuclear spectral broadening function corresponding to the Brownian oscillator model [3] is used to describe the dissipation and energy shift. The theoretical results demonstrate that the nuclear dynamics leads to a decay of the fluorescence variance which shows a non-linear time behavior. The quantum kinetic analysis combined with semi-empirical quantum chemical calculations has been applied to various structured elements in bridged, bichromophoric molecules.
[1] A. Tortschanoff et al., J. Chem. Phys. (1999)-accepted for publication
[2] V. Szőcs and H.F.Kauffmann, J. Chem. Phys. 109, 7431 (1998)
[3] S.Mukamel, Principles of Nonlinear Optical Spectroscopy, (Oxford Uni. Press, New York 1995), Chapter 8