X-RAY PHOTOELECTRON-SPECTRA OF OXYGEN-CONTAINING CERIUM COMPOUNDS

The fine structure of the X-ray photoelectron spectra of the valence e lectrons and those from inner subshells of cerium oxide CeO2, orthonio bate CeNbO4, o-methoxybenzoate CeL3 (L = CH3OC6H4COO-), and diphenylac etate CeL3' . 2H(2)O [L' = (C6H5)(2)CHCOO-] is studied over the range of the electron binding energies from 0 to 1350 eV and compared to the corresponding spectra of electrons of cerium trifluoride CeF3 to gain insight into the origin of such a structure and correlate its paramet ers with the oxidation state of cerium in the compounds. The spectral structure of Ce(III) in the oxygen-containing compounds studied has mu ch in common and differs significantly from the fine structure of the spectrum of Ce(IV) in CeO2, which permits determination of the oxidati on state of cerium in compounds basing on characteristics of the spect ral structure. The experimental data suggest that the structure of, e. g., the spectrum of Ce 3d electrons in CeO2 is due to the final states of the cerium ion: Ce 3d(9)4f(0), Ce 3d(9)4f(1)IVMO(-1) and Ce 3d(9)5 s(1)(5p(5)) 4f(0)ns(np). It is pointed out that the unique final state formally designated by Ce 3d(9)5s(1)(5p(5))4f(0)ns(np) is, state with an additional hole not in the atomic Ce 5s(5p) orbital but in the inn er valence MO (IVMO) a(1g)(t(1u)) for the CeO812- cluster in the O-h s ymmetry consisting predominantly of Ce 5s(5p), O 2s, and O 2p AOs of t he neighboring Ce and O atoms in CeO2.