Hannover 2010 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
MO: Fachverband Molekülphysik
MO 14: Femtosecond Spectroscopy II
MO 14.2: Vortrag
Mittwoch, 10. März 2010, 14:30–14:45, F 102
Investigatin of the hot-S0 model with an excitation energy dependence experiment — •Tiago Buckup1,2, Marie Marek1,2, and Marcus Motzkus1,2 — 1Physikalisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, D-69120 Heidelberg, Germany — 2Physikalische Chemie, Philipps-Universität, D-35043 Marburg, Germany
The ultrafast relaxation dynamics of carotenoids have been challenging spectroscopists for a long time. Energy level models of increasing complexity, containing additional electronic states or vibrationally excited species, have been used to describe the deactivation network of carotenoids. One of such models involves a vibrationally hot ground-state populated via impulsively Raman scattering (IRS). In such a process, the initial excitation pulse must interact two times with the molecule, suggesting the presence of a two-photon excitation scheme. Here we investigate this model by varying the excitation energy in a pump-degenerate four-wave mixing (Pump-DFWM) setup [1-2] applied to lycopene. The experiment shows two distinct excitation dependence regimes obtained for two initial pump delays. In order to clarify this observation, we implemented several deactivation models and simulated the variation of excitation energy on a Pump-DFWM experiment for each model. We found out that a model involving the three well-known electronic states of carotenoids (S2, S1, and S0) and the respective vibrational manifolds is the most suitable scheme to describe the observed energy dependence. Our findings confirm that IRS is an important interaction in carotenoids.