Different cesium oxides have been prepared in situ and studied by near-edge x-ray-absorption fine structure (NEXAFS) measurements. The data have been analyzed by multiple-scattering calculations for two model structures, CsO2 and Cs2O2 using self-consistent final-state potentials. The analysis shows that the sample grown by codeposition of oxygen and cesium has Cs+O2- structure with an O-O distance in the molecular anion of 1.40 +/- 0.05 angstrom, whereas the sample obtained on oxidizing a thin Cs film has Cs2+ O2(2-) structure with an O-O distance of 1.55 +/- 0.05 angstrom. Both distances are larger than the values for the corresponding free ions. Models assuming charge transfer between the alkali and oxygen atoms other than quoted above can be excluded. The analysis also shows that the localized empty states of the O2(2-) anion are sensitive to its surrounding matrix.
Multiple-Scattering analysis of NEXAFS spectra of molecular oxygen anions in differently grown cesium oxides
M Pedio;
1994
Abstract
Different cesium oxides have been prepared in situ and studied by near-edge x-ray-absorption fine structure (NEXAFS) measurements. The data have been analyzed by multiple-scattering calculations for two model structures, CsO2 and Cs2O2 using self-consistent final-state potentials. The analysis shows that the sample grown by codeposition of oxygen and cesium has Cs+O2- structure with an O-O distance in the molecular anion of 1.40 +/- 0.05 angstrom, whereas the sample obtained on oxidizing a thin Cs film has Cs2+ O2(2-) structure with an O-O distance of 1.55 +/- 0.05 angstrom. Both distances are larger than the values for the corresponding free ions. Models assuming charge transfer between the alkali and oxygen atoms other than quoted above can be excluded. The analysis also shows that the localized empty states of the O2(2-) anion are sensitive to its surrounding matrix.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
