Hamburg 2009 – scientific programme
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MO: Fachverband Molekülphysik
MO 7: Femtosekundenspektroskopie 1
MO 7.1: Talk
Tuesday, March 3, 2009, 10:30–10:45, VMP 6 HS-F
Time-resolved investigation of the ultrafast dynamics of Lycopene using Pump-Degenerate Four Wave Mixing (Pump-DFWM) experiment — •Marie Marek, Tiago Buckup, and Marcus Motzkus — Physikalische Chemie, Philipps Universität Marburg, D-35043 Marburg, Germany
Carotenoids are one of the most wide spread class of natural molecules fulfilling a wide range of biological tasks in bacteria and plants. In spite of the importance of carotenoids in Photobiology the dynamics of the excited states are still not clear. In this work we expand our knowledge about the excited states of carotenoids and apply Pump-Degenerate Four Wave Mixing (Pump-DFWM) to an important member of the carotenoid family, lycopene. In this two-dimensional technique, an Initial Pump pulse promotes the system to the excited state, which is then probed by the succeeding DFWM sequence. We focus particularly on the internal conversion between the S2 and S1 state with high temporal and spectral resolution. By measuring the evolution of the amplitudes and frequency shifts of the excited state vibrations we show that the symmetric C=C stretching mode plays a dominant role for the internal conversion. Furthermore, similar to our previous study on β-carotene [1], a low-lying vibrationally hot state is also identified for lycopene in solution. Besides that, observation of a low-frequency mode at 370 cm−1 is discussed under the light of lycopene isomers distribution in the ground state.
[1] J. Hauer, T. Buckup, M. Motzkus, JPCA 111, 2007, 10517.