SITE-SELECTIVE AND STARK SPECTROSCOPY OF THE SERIES [OS(2,2'-BIPYRIDINE)(3-X)(2,2'-BIPYRIDINE-D(8))(X)](2+)(X=0-3) IN SINGLE-CRYSTAL [RU(2,2'-BIPYRIDINE)(3)](PF6)(2) - LOCALIZATION OF AN INTRAMOLECULAR TRIPLET METAL-TO-LIGAND CHARGE-TRANSFER EXCITON BY PARTIAL DEUTERATION

Selective luminescence and excitation spectroscopy and Stark experiments of the title systems are reported. Dramatic differences of the x=1 and x=2 spectra, in comparison with the x=0 and x=3 spectra are observed. The lowest-excited state in the x=1 and x=2 spectra is a charge-transfer excitation localized on the protonated ligand(s). A superposition of "deuterated" and "protonated" transitions is observed for the x=1 and x=2 systems in the excitation spectra. The deuteration shift (≈32 cm-1) is much larger than the excitation exchange interaction β between the metal-ligand subunits. |β| is ≈2 cm-1, as directly determined from the observed splittings (5-7 cm-1) of I, the lowest-energy electronic origin. Stark shifts confirm the charge transfer character of the lowest-excited states. The splittings and relative intensities of the origins and their Stark effect can be quantitatively described by an exciton formalism. © 1995 American Institute of Physics.