München 2004 – scientific programme
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MO: Molekülphysik
MO 12: Poster I
MO 12.13: Poster
Tuesday, March 23, 2004, 14:00–16:00, Schellingstr. 3
The investigation of excited-state dynamics of polyatomic molecules by means of fs time-resolved four-wave mixing spectroscopy — •Maksimenka Raman1, Benjamin Dietzek1, Torsten Siebert1, Wolfgang Kiefer1, and Michael Schmitt1,2 — 1Institut für Physikalische Chemie, Universität Würzburg, Am Hubland, 97074, Würzburg — 2Institut für Physikalische Chemie, Universität Jena, Helmholtzweg 4, 07743 Jena
The evolution of molecules in their excited states is of great interest in physics, chemistry and biology, since the absoption of a photon may e.g. lead to photoreactions. Therefore it is important to explore the relaxation pathways of molecules after photoexcitation. Especially the roles of certain nuclear degrees of freedom invloved in radiationless transitions need to be elucidated. We demonstrate that different fs time-resolved four-wave mixing schemes can be applied to investigate the excited-state dynamics of polyatomic molecules. Thus coherent anti-Stokes Raman scattering (CARS) is capable to selectively interrogate the role of specific Raman modes. This technique has been applied to directly observe the redistribution of vibrational energy between different modes of Stilbene 3 taking place after photoexcitation. Time-resolved CARS was used to identify shifts of normal modes positions in the excited state in comparison to the ground state. Furthermore, transient grating spectroscopy was used to characterize radiationless transitions between various electronic states in azulene derivatives. In summary, different fs four-wave mixing schemes were successfully applied to characterize dynamical processes in polyatomic molecules induced by photoexcitation.