München 2004 – scientific programme
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MO: Molekülphysik
MO 7: Femtosekundenspektroskopie: Protontransfer + Energiefluss
MO 7.6: Talk
Monday, March 22, 2004, 15:15–15:30, HS 315
Fs-timeresolved 2-Photon Spectroscopy of the Carotenoids in Photosystem 1 and other Photosynthetic Protein Complexes — •Peter Jomo Walla1,2, Michael Hilbert2, Axel Wehling1, Dirk Schwarzer2, Peter Kutne2 und Sebastian Kuehn2 — 1Technical University of Brunswick, Institute for physical and theoretical Chemistry, Hans-Sommerstr. 10, D 38106 Brunswick, Germany — 2Max-Planck-Institute for Biophysical Chemistry, Am Fassberg, D 37077Goettingen, Germany
Carotenoids play a crucial role as light-harvesting pigments in photosynthesis and in the regulation of the energy flows in the photosynthetical apparatus. In Light-harvesting complex II e.g., which collects more than 50 % of the light used for photosynthesis on earth, carotenoids contribute about 30 % to this huge amount of collected energy. However, a detailed insight in the underlying mechanisms was very often impossible due the optical forbidden character of the first excited state of carotenoids, S1. This is because it has the same Ag symmetry as the ground state, S0. Therefore for many photosynthetical complexes there is still neither any knowledge about the S1 state energies nor about the corresponding energy transfer mechanisms. An elegant approach to gain more insight into these questions is the investigation via 2-photon excitation because Ag-Ag-transitions are generally 2-photon allowed. We present the results of 2-photon excitation spectra as well as Fs-2-photon pump-probe and Fs-2-photon up-conversion experiments on Photosystem 1 of Synecochoccus Elongatus and other photosynthetical protein complexes.