We present synchrotron-excited oxygen x-ray K-emission spectroscopy ͑O K␣ XES͒ and oxygen x-ray absorption spectroscopy ͑O 1s XAS͒ spectra of transition-metal ͑TM͒ oxides MnO, CoO, and NiO. The comparison of oxygen K-emission and absorption spectra to valence band photoemission and bremsstrahlung isochromat spectra measurements shows that O 1s XAS is not strongly influenced by the core hole effect, whereas the TM 2p XAS significantly shifts to a lower energy. New and effective methods for determining the band gap and anion-to-cation cation charge-transfer energies of the oxides from the measured spectra are presented and applied, and the combination of O XAS and XES is shown to agree well with the results of numerical electronic structure methods applied to strongly correlated oxides. For MnO, the charge-transfer energy is found to be 6.6 eV and the band gap is 4.1 eV; for CoO, the values are 6.1 and 2.6 eV and for NiO, the values are 5.4 and 4.0 eV.

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Results of measurements of sulphur x-ray emission spectra of CuS and , excited by synchrotron radiation near the sulphur 2p threshold, are presented. An excitation energy dependence of the sulphur XES is only observed for CuS, and is attributed to the presence of inequivalent sulphur atoms in CuS. Two thirds of the sulphur atoms form dimers (as in ) while the remaining ones are single (as in ). This conclusion is confirmed by XPS measurements and LMTO band structure calculations for CuS, and . It is shown that selective excitation of x-ray emission valence spectra can be used to determine the atom-decomposed partial density of states for inequivalent sites in solids, occupied by chemically identical species.

A tight‐binding linearized muffin‐tin orbital method was applied for the calculation of the densities of states (DOS) for TiO2 with the rutile structure in the wide energy region of the conduction band. The calculated partial DOS of titanium and oxygen were compared with the experimental Ti 2p total electron yield spectrum (TEY), which was measured in the present work, and the Ti 1s x‐ray absorption spectrum, O 1s TEY and bremstrahlung isochromat spectrum taken from the literature. We found that in the energy region higher than ∼6 eV above the bottom of the conduction band the fine structure of experimental absorption spectra follows the distribution of the corresponding partial DOS. In connection with this, one does not need to use any satellite mechanism for an interpretation of these spectra. In the region of vacant Ti 3d states (up to ∼6 eV), correspondence between the experimental and calculated splitting of t2g and eg subbands is observed in all spectra except Ti 2p TEY. As we showed using atomic calculations, this is connected with the Ti 2p53d1 multiplet in the final state of absorption which leads to suppression of the intensity of lower states of the t2g subband in Ti 2p TEY of TiO2. As a result, t2g–eg splitting extracted from Ti 2p3/2 and Ti 2p1/2 TEY is less than in Ti 3d DOS and other experimental spectra (Ti 1s XAS and O 1s TEY) in which an interaction of core level vacancy with photoelectron is absent owing to the delocalized character of valent states. Copyright © 2002 John Wiley & Sons, Ltd.

A full study of the electronic structures of FeCr2S4 and Fe0.5Cu0.5Cr2S4 is reported based on x-ray photoelectron spectra (valence band and core levels), x-ray emission spectra (Fe Lα, Cu Lα, Cr Lα, S Kβ1,3 and S L2,3) and ab initio TB-LMTO band structure calculations. In the valence band of FeCr2S4, the Fe 3d states are found to be more localized than the Cr 3d states, which dominate at the Fermi level. In Fe0.5Cu0.5Cr2S4, the distribution of Cr 3d (Cr3+) states is unchanged and the Cu ions were found to be in the Cu+ state.