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MO: Fachverband Molekülphysik

MO 13: Photochemistry

MO 13.6: Vortrag

Montag, 19. März 2007, 17:45–18:00, 6B

Precursor molecules for organic synthesis: A model system for initial dissociation dynamics of diphenylmethylchloride — •Benjamin Fingerhut, Dorothee Geppert, and Regina de Vivie-Riedle — LMU Department Chemie, Butenandt-Str. 11, 81377 München, Germany

Our investigations focus on the laser induced dissociation dynamics of diphenylmethylchloride and its derivatives which occur on a femtosecond timescale. An understanding of the initial fragmentation pathways gives insight into the formation of carbo-cations in solution, key intermediates in organic synthesis.

For an accurate description of the excitation and the dissociation process at least three electronic states have to be taken into account by quantum chemical methods. A π^* - σ^*-charge-transfer connects the Franck-Condon region with a repulsive potential, followed by non-radiative relaxation into the competing reaction channels. The branching ratio between the bound and the repulsive fragmentation pathway is facilitated by at least one conical intersection and defined by appropriate non-adiabatic-coupling-matrix-elements.

We present a model system, based on our ab-initio data which is suitable to describe the multidimensional dissociation process in a reduced reactive coordinate subspace. Herein we are able to follow the dissociation dynamics via multiple conical intersections after femtosecond laser excitation.