Robert L. Blackbourn

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

Abstract 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.

Optical electron transfer processes. The dependence of intervalence line shape and transition energy on chromophore concentration

Abstract Optical electron transfer in the mixed-valence cation of biferrocenylacetylene (BF + ) has been examined in CD 2 Cl 2 solvent. The intervalence absorption line shape is relatively narrow at both low and high chromophore concentrations, but broader at intermediate concentrations. The transition energy for metal-to-metal charge transfer increases from ≈4440 cm −1 at infinite dilution to 5995 cm −1 for 3.8 mM BF + . Related effects exist due to added electrolyte. Neither the electrolyte nor chromophore concentration effects are expected from a simple reading of electron transfer theories. Nevertheless, both phenomena can be understood and within the context of theory upon careful consideration of the effects of ion-pairing (and tripling) equilibria upon electron-transfer energetics.