Frankfurt 2006 – wissenschaftliches Programm
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MO: Molekülphysik
MO 45: Biomolecules II
MO 45.3: Vortrag
Mittwoch, 15. März 2006, 17:00–17:15, H10
Energy flow in β-carotene after multiphoton excitation using tunable sub-30 fs pulses in the near-IR — •Tiago Buckup, Alexander Weigel, and Marcus Motzkus — Physikalische Chemie, Phillips Universität Marburg, 35043 Marburg, Germany
Carotenoids perform a variety of critical functions in nature, which are strongly dependent on their energy deactivation network. The classical three-level-scheme of carotenoids describes the deactivation of the photoexcited S2 state by ultrafast internal conversion to the dark S1 state which in turn decays to the ground state S0 on the picosecond time scale. As it has been shown in previous contributions, the S1 state can be excited via a two-photon transition directly from S0. Here we extend the concept of multiphoton Pump-Probe spectroscopy to beta-carotene in a new excitation range (900-1100 nm) using tunable sub-30 fs pulses. Besides the well-known S1 deactivation, long-lived contributions can also be observed in the blue region of the visible spectra and in the near-IR. These two contributions are associated with the absorption of a triplet and a cation state, respectively. The presence of additional dark states is also considered and a model taking into account all observations is presented.