Chemistry

The Proper Mix in Electron Transfer

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Science  18 May 2001:
Vol. 292, Issue 5520, pp. 1265
DOI: 10.1126/science.292.5520.1265b

Electronic excitations of a molecule can change its normal modes of vibration, as was pointed out by Duschinsky in the late 1930s. The excited state of the molecule can have a different symmetry than the ground state, and thus the computation of the overlap integrals of vibrational states, or Franck-Condon factors, in principle requires a multidimensional calculation to account properly for the resulting mixing of different vibrational levels. In a pair of papers, Sando and co-workers examine how Duschinsky mixing affects transition states for electron transfer reactions, for which many studies have used metal complexes of high symmetry. They find that the effects can be large; for example, the parabolas that describe the “inverted region” of electron transfer are flattened out in some cases. Although individual totally symmetric modes are affected more strongly, the larger number of nontotally symmetric modes add together to a sizeable contribution. — PDS

J. Phys. Chem. A, in press.

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