Hamburg 2009 – scientific programme

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MO: Fachverband Molekülphysik

MO 7: Femtosekundenspektroskopie 1

MO 7.2: Talk

Tuesday, March 3, 2009, 10:45–11:00, VMP 6 HS-F

Degenerate Four-Wave-Mixing Studies on Bacteriorhodopsin — •Jan Philip Kraack, Tiago Buckup, and Marcus Motzkus — Physikalische Chemie, Philipps-Universität Marburg, D-35032 Marburg, Germany

Bacteriorhodopsin (bR) is a membrane protein which enables the organism Halobacterium salinarum (Hs) to convert visible light into chemical energy. This is driven by a cyclic process on a millisecond timescale, which is initiated by the isomerization of the protein-bound chromophore all-trans retinal on the sub-picosecond timescale. In this work, time-resolved degenerate four-wave-mixing (DFWM) experiments are presented on the light-adapted form of this model system to investigate the photoinduced wave packet dynamics in electronic ground and excited states on the sub-20 femtosecond timescale. It has been shown that this coherent Raman-technique can give insight to electronic population as well as wave packet dynamics. The observed signals are discussed in dependence of the excitation wavelength as well as the effect of time ordering of the three DFWM-pulses generating the signal. It is shown, that low- as well as high-frequency vibrational motion can be observed due to the homodyne signal-generation. The origin of wave packet motion is discussed and an interpretation in terms of the known models for the initial molecular dynamics is given.