Electron dynamics within Ru-2,2′-bipyridine complexes -: an N1s core level excitation study

The dynamics of electron transfer within an excited ruthenium complex as well as between a ruthenium complex and a nanostructured TiO2 film is addressed on the core hole few femtosecond lifetime scale. The ruthenium complexes studied are Ru(bpy)(3)(2+) . 2Cl(-) (where bpy is 2,2'-bipyridine) as well as Ru(bpy)(2)(dcbpyH(2))(2+) . 2PF(6)(-) (dcbpy is 4,4'-di-carboxy-2,2'-bypyridine) anchored to a nanostructured TiO2 surface, where the latter system constitutes the photoactive part of a dye-sensitized solar cell. The N1s core level of the ruthenium complexes was excited by using synchrotron radiation, and the experimental techniques used were X-ray absorption spectroscopy (XAS) and resonant photoelectron spectroscopy (RPES). The occupied molecular orbital structure and the N1s partial density of unoccupied states are mapped and compared to calculated orbital structures. (C) 2002 Elsevier Science B.V. All rights reserved.