Hannover 2013 – scientific programme

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MO: Fachverband Molekülphysik

MO 14: Poster 1: Cluster, Femtosecond Spectroscopy

MO 14.19: Poster

Tuesday, March 19, 2013, 16:00–18:30, Empore Lichthof

Open chain carotenoids with N=9-13 conjugated double bonds studied by multidimensional spectroscopy — •Takeshi Miki, Marie S.Marek, Tiago Buckup, and Marcus Motzkus — Physikalisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, D-69120 Heidelberg, Germany

All-trans carotenoids are ubiquitous biomolecules with a central function in photobiology. Detailed investigation of the initial energy dissipation pathway following photo-excitation in carotenoids proved to be challenging for ultrafast optical spectroscopy. In this work, we apply pump-degenerate four wave mixing (pump-DFWM) to a series of carotenoids with the conjugated double bond lengths from N = 9 (neurosporene), 10 (spheroidene), 11 (lycopene) and 13 (spirilloxanthin). We concentrate on the initial ultrafast dynamics (< 1 ps) and how high-frequency modes evolve in this time window. Raman active modes differ on the dependence of their amplitude and frequency on the population relaxation. For shorter chain carotenoids, high-frequency Raman active modes are present directly after the excitation of S2 and showed less pronounced dependences on the population relaxation than the modes in the longer chain carotenoids, where state specific modes can be clearly identified.