Determination of vanadium valence in hydrated compounds

X-ray photoelectron spectroscopy was used to determine the chemical shift and full-width at half-maximum intensity of the V4+ and V5+ cations peaks in the vanadium pentoxide matrix. It was found that the binding energy of V4+ ions shifts to the lower energy side of about 1.3 eV as compared with the main V5+ ions in the matrix. The V 2p(3/2) line width for tetravalent vanadium ions in xerogels is actually the same as for pentavalent ions. The fitting procedure of X-ray photoelectron spectra permits determination of the relative concentrations of the reduced vanadium ions with an accuracy of about 3%.