Experimental assessment of dynamic structural parameters for homogeneous and interfacial charge-transfer reactions: case studies based on time-dependent Raman scattering methods

The application of time-dependent scattering methodologies to dynamic structural problems involving charge transfer reactions is described. We show experimentally that a time-dependent analysis of resonance-enhanced Raman scattering can lead to a complete mode-by-mode description of the vibrational structural changes accompanying charge transfer and, therefore, a complete description of the vibrational activation barrier to charge transfer. (In other words, all force constants, all mode displacements, all bond-length displacements, and all individual energy components of the barrier can be determined.) The strategy is illustrated with case studies of internal (metal-to-ligand) charge transfer, ligand-bridged metal-to-metal charge transfer, outer-sphere charge transfer, and interfacial charge transfer.