Search results for "X-RAY-ABSORPTION"

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Stoichiometry-related Auger lineshapes in titanium oxides: Influence of valence-band profile and of Coster-Kronig processes

2004

International audience; The ability to determine the nature and the occurrence of defects is a central need of ceramic surface chemistry. In titanium oxides, the Ti-LMV Auger decays line shape is very sensitive to the titanium degree of oxidation, and has long been empirically used as a qualitative probe of the stoichiometry. In the present work, resonant Auger and resonant valence-band measurements at the Ti-L2,3 edges in TiO2, TiO2–x and metallic titanium provide a clear evidence that the evolutions of the Ti-LMV Auger line shape are due to drastic changes in the valence-band profile and in the probability of L2L3V Coster-Kronig decay processes when a fraction of titanium ions is reduced.…

PACS: 71.20.-b 32.80.Hd 77.84.Bw 82.80.Pvoxidationchemistry.chemical_element02 engineering and technologyceramics01 natural sciencesElectron spectroscopy71.20.-b; 32.80.Hd; 77.84.Bw; 82.80.PvIonAugerX-RAY-ABSORPTION; SURFACE-DEFECTS; RUTILE TIO2; Resonant AugerMetalsymbols.namesakephotoelectron spectra0103 physical sciencesRUTILE TIO2titanium010306 general physicstitanium compoundsAuger electron spectroscopyFermi levelvalence bandsResonant Auger021001 nanoscience & nanotechnologyCondensed Matter PhysicsSURFACE-DEFECTSElectronic Optical and Magnetic Materialsstoichiometrychemistryvisual_artX-RAY-ABSORPTIONsymbolsvisual_art.visual_art_mediumFermi levelspectral line breadthAuger electron spectraAtomic physics0210 nano-technologyStoichiometryTitanium
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EXAFS studies on the local structure of Er3+ ions in silica xerogels co-doped with aluminium

2001

The local environment around Er3+ ions in wet and densified (at 900°C) silica xerogels (pure and co-doped with aluminium) has been studied at the Er L3-edge by X-ray absorption spectroscopy using the fluorescence detection technique. The radial distribution functions (RDF), reconstructed from X-ray absorption fine structure (EXAFS), show several changes in the local co-ordination of erbium ions upon densification: shortening of the Er-O and Er-Si/Al distances, decrease of the co-ordination numbers and broadening of the Er-O RDF. The effect of Al co-doping is clearly discerned by EXAFS in both the first and second co-ordination shells for densified gels and mainly in the second shell for wet…

X-RAY-ABSORPTION; GEL GLASS; FLUORESCENCE; silica xerogels; erbiumGEL GLASSMaterials scienceAbsorption spectroscopyExtended X-ray absorption fine structureDopingAnalytical chemistrychemistry.chemical_elementMineralogyCondensed Matter PhysicsSilica xerogelsFluorescenceElectronic Optical and Magnetic MaterialsIonErbiumerbiumchemistryAluminiumX-RAY-ABSORPTIONMaterials ChemistryCeramics and CompositesFLUORESCENCEAbsorption (chemistry)Aluminum
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