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MO: Fachverband Molekülphysik
MO 4: Femtosekundenspektroskopie II
MO 4.4: Talk
Monday, March 10, 2008, 17:15–17:30, 3G
Femtosecond Dynamics of Phenylcarbenes — •Bastian Noller1, Ingo Fischer1, Lionel Poisson2, and Jean-Michel Mestdagh2 — 1Institut für Physikalische Chemie, Universität Würzburg, Deutschland — 2Laboratoire Francis Perrin, CEA Saclay, France
Carbenes play an important role in combustion chemistry and interstellar space and have gained considerable interest in synthesis over the last years. The electronic states of carbenes often have very small energy gaps between each other and are of considerable interest as a "benchmark" for improving quantum mechanical methods. The photophysics of carbenes is not well investigated due to the experimental challenge. The dynamics of several phenylcarbenes (Ph-C-R), with a variety of substituents (i.e. R=CH3, CF3, Cl), were investigated by femtosecond time-resolved pump probe spectroscopy in a free jet. REMPI spectra were recorded with a nanosecond laser setup. The carbenes were produced by jet flash pyrolysis of diazirines. Time-of-flight mass spectrometry, photoion- and photoelectron imaging were employed as detection methods in the femtosecond time-resolved experiments. The excited state dynamics depended on the substituents (R) and will be compared to models based on qualitative excited state calculations. Preliminary results indicate that conical intersections along the rotation coordinate of the group R against the phenyl ring and/or along the coordinate of a 1,2-H-shift in the excited state play an important roles for state deactivation.