Ultrafast electron localization dynamics following photo-induced charge transfer

Molecular dynamics occurring in the earliest stages following photo-induced charge transfer were investigated. Femtosecond time-resolved absorption an isotropy measurements on [Ru(bpy)(3)](2+), where bpy is 2,2'-bipyridine, re veal a time dependence in nitrile solutions attributed to initial delocaliz ation of the excited state over all three Ligands followed by charge Locali zation onto a single Ligand. The localization process is proposed to be cou pled to nondiffusive solvation dynamics. In contrast, measurements sampling population dynamics show spectral evolution associated with wave packet mo tion on the excited state surface that is independent of solvent. The resul ts therefore reveal two important contributions to the evolution of charge transfer states in condensed phase, one that is strongly coupled to the sur rounding environment and another that follows a potential internal to the m olecule.