The electronic structure of the cis-bis(4,4′-dicarboxy-2,2′-bipyridine)-bis(isothiocyanato)ruthenium(II) complex and its ligand 2,2′-bipyridyl-4,4′-dicarboxylic acid studied with electron spectroscopy

The electronic structure of the dye complex cis-bis(4,4′-dicarboxy-2,2′-bipyridine)-bis(isothiocyanato)ruthenium(II) as well as that of its ligand 2,2′-bipyridine-4,4′-dicarboxylic acid has been investigated with electron spectroscopy. Valence level spectra have been studied with respect to photoelectron angular distributions and photon energy dependence. The experimental information coupled with semi-empirical INDO/S calculations provides a mapping of the orbital parentage of the dye complex and its ligands. The energy levels of the dye complex in the context of a sensitized semiconductor (nanostructured titanium dioxide) surface are related to the bands of the semiconductor.