Electronic excitation in a catalytic support oxide, CeO2

X-ray resonant Raman scattering (XRRS) measurements were performed on a sin gle crystal of ceria, CeO2, near the Ce Lm edge. Ceria is an important comp onent of automotive catalytic converters, and helps to maintain the oxygen pressure in the vicinity of metal catalysts through the valence change Ce4 <----> Ce3+. The XRRS spectra show rich features of electronic excitations in ceria involving various f state occupations of cerium that change with temperature and/or surface composition. Determining the electronic process that leads to valence change would facilitate the understanding of the buff ering function of ceria. (C) 2000 Elsevier Science Ltd. All rights reserved .