Mn K  x-ray emission spectra provide a direct method to probe the effective spin state and charge density on the Mn atom and is used in an experimental study of a class of Mn oxides. Specifically, the Mn K  line positions and detailed spectral shapes depend on the oxidation and the spin state of the Mn sites as well as the degree of d covalency/itinerancy. Theoretical calculations including atomic charge and multiplet effects, as well as crystal-field splittings and covalency effects, are used as a guide to the experimental results. Direct comparison of the ionic system MnF 2 and the covalent system MnO reveals significant changes due to the degree of covalency of Mn within atomic-type Mn K  simulations. Moreover, comparisons of measurement with calculations support the assumed high spin state of Mn in all of the systems studied. The detailed shape and energy shift of the spectra for the perovskite compounds, LaMnO 3 and CaMnO 3 , are, respectively, found to be very similar to the covalent Mn 3ϩ-Mn 2 O 3 and Mn 4ϩ-MnO 2 compounds thereby supporting the identical Mn-state assignments. Comparison to the theoretical modeling emphasizes the strong covalency in these materials. Detailed Mn K  x-ray emission results on the La 1Ϫx Ca x MnO 3 system can be well fit by linear superpositions of the end member spectra, consistent with a mixed-valent character for the intermediate compositions. However, an arrested Mn-valence response to the doping in the xϽ0.3 range is found. No evidence for Mn 2ϩ is observed at any x values seemingly ruling out proposals regarding Mn 3ϩ disproportionation. ͓S0163-1829͑99͒02231-6͔
We study 1s and 2p hard x-ray photoemission spectra (XPS) in a series of late transition metal oxides: Fe2O3 (3d 5 ), FeTiO3 (3d 6 ), CoO (3d 7 ) and NiO (3d 8 ). The experimental spectra are analyzed with two theoretical approaches: MO6 cluster model and local density approximation (LDA) + dynamical mean-field theory (DMFT). Owing to the absence of the core-valence multiplets and spin-orbit coupling, 1s XPS is found to be a sensitive probe of chemical bonding and nonlocal charge-transfer screening, providing complementary information to 2p XPS. The 1s XPS spectra are used to assess the accuracy of the ab-initio LDA+DMFT approach, developed recently to study the material-specific charge-transfer effects in core-level XPS.
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