Open AccessEXAFS analysis of the L 3 edge of Ce in CeO 2 : effects of multi‐electron excitations and final‐state mixed valence
Author(s) -
Fonda E.,
Andreatta D.,
Colavita P. E.,
Vlaic G.
Publication year - 1999
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s0909049598010280
Subject(s) - extended x ray absorption fine structure , cerium , valence (chemistry) , x ray absorption spectroscopy , cerium oxide , xanes , oxidation state , catalysis , k edge , spectral line , chemistry , absorption spectroscopy , electronic structure , materials science , inorganic chemistry , physics , computational chemistry , optics , biochemistry , organic chemistry , astronomy
Cerium oxide (IV) (CeO 2 ) is extensively employed in heterogeneous catalysis, particularly as a promoter of noble metal action in three‐way catalysts. For this reason there is a great scientific and economical interest in the development of any possible chemical or structural analysis technique that could provide information on these systems. EXAFS spectroscopy has revealed itself as a powerful technique for structural characterization of such catalysts. Unfortunately, good quality K ‐edge spectra of cerium are not yet easily obtainable because of the high photon energy required (>40 keV). On the other hand, at lower energies it is easy to collect very good spectra of the L 3 edge (5.5 keV), but L 3 ‐edge spectra of cerium (IV) are characterized by the presence of two undesired additional phenomena that interfere with EXAFS analysis: final‐state mixed‐valence behaviour and intense multi‐electron excitations. Here, a comparative analysis of the K , L 3 , L 2 and L 1 edges of Ce in CeO 2 has been made and a procedure for obtaining structural parameters from L 3 ‐edge EXAFS, even in the presence of these features, has been developed. This procedure could allow further studies of catalytic compounds containing tetravalent cerium surrounded by oxygen ligands.