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MO: Fachverband Molekülphysik
MO 21: Femtosecond Spectroscopy V
MO 21.5: Talk
Thursday, March 21, 2013, 12:00–12:15, F 102
Combined Marcus-Smoluchowski model for electron transfer from photo-generated benzhydryl to chlorine radical — •Sebastian Thallmair1,2, Christian F. Sailer2, Benjamin P. Fingerhut1, Eberhard Riedle2, and Regina de Vivie-Riedle1 — 1Department Chemie, LMU München — 2LS für BioMolekulare Optik, LMU München
The precise mechanism and dynamics of the photo-generation of carbocations and carbon radicals is a fundamental issue in organic chemistry. The role and importance of electron transfer (ET) subsequent to homolytic bond cleavage of benzhydryl chloride that leads to the formation of carbocations is discussed. We combine a distance dependent ET model given by Marcus theory with the Smoluchowski diffusion model. It is based on a hard sphere model starting at contact distance. We consider time dependent population distributions for the radical pairs and the ion pairs and include the radial distribution function of the solvent as well as the Coulomb interaction for the ion pairs in the inter pair potentials. Geminate recombination, ET, diffusion and full solvent stabilization due to the formation of a complete solvent shell are included in terms of distant dependent rates. A close accord with the experiment can only be reached if a broad distance distribution of the nascent radical pairs is assumed. The fast depletion of the radical pair distribution at small distances leads to the observed non-single exponential ET dynamics. Our results demonstrate that traditional descriptions of reaction mechanisms based on the concept of contact and solvent-separated pairs have to be reassessed.