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MO: Fachverband Molekülphysik

MO 56: Poster: Femtosecond Spectroscopy

MO 56.6: Poster

Donnerstag, 22. März 2007, 16:30–18:30, Poster A

Investigation of Molecular Dynamics in all-trans-β-Carotene Using Femtosecond Pump-FWM Spectroscopy — •Abraham Scaria, Vinu Namboodiri, Jakow Konradi, and Arnulf Materny — International University Bremen (Jacobs University Bremen as of spring 2007), Germany

The many degrees of freedom offered by four wave mixing (FWM) spectroscopy makes it a versatile tool for the investigation of complex molecular dynamics. Here, we have used pump-FWM spectroscopy on a femtosecond time scale to follow the molecular dynamics occurring in all-trans-β-carotene. The transients show clear signatures of the different spectroscopic pathways that the molecules follow after the excitation. This provides a deeper understanding of the excited state dynamics of carotenoids, which is important due to their active participation in light harvesting process. The initial pump pulse excites the molecules into the first optically accessible state (S₂). From there it undergoes a fast internal conversion (IC) in to the electronic dark state (S₁). The FWM process is chosen to be resonant with S₁ and a higher lying excited state (S_n). The results of the dependence of the initial pump power as well as the pump wavelength on the transients will be presented. Possible contributions of other electronic states are discussed.