Charge transfer bands in luminescence excitation spectra of Eu3+ in salts of europium and isomers of pyridinedicarboxylic acids

Within Eu3+ ion luminescence excitation spectrum in salt of europium and 3,4-pyridinecarboxylic acid in 360-400 nm region one detected ligand-cation charge transfer band not found in spectra of salts of europium and 2,6- and 2,3-pyridinedicarboxylic acids. Occurrence of the mentioned band points to essential efficiency of energy transmission through charge transfer state caused by higher polarizability of a ligand in first compound. A certain effect of quenching of wide-band luminescence of organic molecules by lanthanide ions with a low oxidation-reduction potential is assumed to result from transmission of energy through excited states of ligand charge transfer to lanthanide ion