Epitaxial thin films of LaNiO 3−x were deposited by using a reactive d.c. magnetron sputtering technique. High-energy X-ray photoelectron spectroscopy was used to analyze the composition and valence states of La and Ni in the films after long time aging in atmosphere. The obtained results show the existence lanthanum and nickel in oxide and hydroxide chemical states. The oxygen exists in four chemical states: lattice oxides, hydroxyl groups and in adsorbed water. Comparison of the spectra recorded at normal emission and grazing emission angle revealed that the hydroxyl group's concentration is mostly present at the surface of the film.

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Problems of the definition of vanadium chemical states in the mixed valency compounds are examined. The statistical analysis of the literature data on the values of binding energy and full width at half maximum (FWHM) of V 2p 3/2 peaks in different vanadium oxides is carried out.X-ray photoelectron spectroscopy was used to determine the chemical shift and FWHM of V 2p peaks of V 4+ and V 5+cations in the vanadium pentoxide matrix of hydrated vanadium compounds HV12O31·nH2O and (VO)V12O31·nH2O, prepared by using sol-gel technology. It was found that the binding energy of V 4+ ions shifts to the lower energy side of about 1.3 eV as compared to the main V 5+ ions in the matrix. The V 2p 3/2 line width for tetra-valent vanadium ions in xerogels is actually the same as for penta-valent ions.