Frankfurt 2006 – scientific programme

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MO: Molekülphysik

MO 45: Biomolecules II

MO 45.1: Talk

Wednesday, March 15, 2006, 16:30–16:45, H10

Femtosecond Two-Photon Spectroscopy determines hidden carotenoid dark state dynamics — •Peter Jomo Walla^1,2, Wehling Axel², and Michael Hilbert¹ — ¹Max-Planck-Institut für Biophysikalische Chemie, Am Faßberg 11, D-37077 Göttingen — ²Institut für Physikalische und Theoretische Chemie, Abt. Biophysikalische Chemie, Hans-Sommerstr. 10, D-38106 Braunschweig

Carotenoids play an important role as light-harvesting pigments and in the regulation of the energy flows in the photosynthetical apparatus under changing environmental light conditions. However, a detailed insight in the underlying mechanisms was very often impossible due the optical forbidden character of the first excited state of carotenoids, Car S1. This is because it has the same Ag symmetry as the ground state, Car S0. An elegant approach is the investigation via two-photon excitation because Ag->Ag-transitions are generally two-photon allowed. Using this approach we access directly and selectively the forbidden state and gain important information about the light harvesting mechanisms and the regulation of excessive excitation energy under high-light conditions in the photosynthetic apparatus. We will present latest femtosecond two-photon results from several photosynthetic protein complexes and real plants. With these data it is possible to gain a detailed understanding of the energy transfer mechanisms and the regulation of the photosynthetic apparatus in living plants.