POSITION-DEPENDENT DEUTERIATION EFFECTS ON THE NONRADIATIVE DECAY OF THE (3)MLCT STATE OF TRIS(BIPYRIDINE)RUTHENIUM(II) - AN EXPERIMENTAL EVALUATION OF RADIATIONLESS TRANSITION THEORY

The nonradiative decay of the lowest electronically excited triplet st ates ((3)MLCT) of the title compound is studied and discussed on the b asis of a previously developed theoretical framework. Extensive data o n the luminescence lifetimes and resonance Raman intensities for a num ber of deuteriated analogues have been obtained in order to establish the role of the skeletal bipyridine vibrations in the nonradiative dea ctivation process. Careful inspection of the results documents positio n-dependent deuteriation effects on the nonradiative decay rate for Ru (bpy)(3)(2+). A model of the nonradiative decay process, incorporating the frequencies and intensities of a large number of totally symmetri c acceptor vibrations, has been applied to the data for all the availa ble isotopomers. A weak correlation between the observed and calculate d relative nonradiative decay rates exists when only acceptor modes ar e assumed to vary with ligand deuteriation. However, inclusion of non- totally symmetric in-plane promoter vibrations yields calculated rates which are in an excellent agreement with the experimental data.