XPS STUDIES OF A SERIES OF Ce(Ⅳ) AND Ce(Ⅲ) COMPOUNDS

XPS from Ce3d level of eerie ammonium sulfate, eerie sulfate, ceric-benzilic acid complex, eeric iodate, cerie peroxide and cerie dioxide were recorded. All of the spectra exhibit two distinct sets of structure corresponding to trivalent and tetravalent cerium ions. The Ce3d XPS of cerous oxalate, cerous sulfate, cerousbenzilic acid complex, cerous iodate and cerous chlorite were also recorded. All of them only show one set of spin-orbit splitting structure with shake-down satellites at lower binding energy side of the main peaks. The Ols spectrum of CeO2 after heating in vacuum shows two peaks with an energy separation of 2.5eV, which reflects that the valence fluctuation Ce(4f0)O(2pπ)←→Ce(4f1)O(2pn+1) may be responsible for the mixed valency in these nominal tetravalent cerium compounds.