We present soft-x-ray absorption spectra (XAS) of LaCo03 taken at different temperatures (80 -630 K). The shape of the multiplets in the Co 2p XAS spectra conveys information on the symmetry and spin of the ground state. The 0 1s XAS spectra are related to unoccupied metal bands through covalent mixing. The changes in the spectra taken at different temperatures provide information on the spin-state transition in this compound. At low temperature, 80 and 300 K, the material is in a highly covalent low-spin state. The main contribution to the ground state in this case is given by t2g(' A l ) with an occupancy of 0.56. At higher temperature, 550 and 630 K, the results indicate a gradual transition to a mixed-spin state. The main contribution to the high-spin part of the mixture is given by t2geg('T2 ) with an occupancy of 0.71. There is no evidence of charge disproportionation in the temperature range 80 -630 K. The 0 1s XAS spectra reAect important changes in the unoccupied Co 3d bands across the spin-state transition.

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Experimental data and theoretical calculations are shown for Pr 3d and 4d x-ray photoemission spectra (XPS) of Fr&03. The observed spectral structures are well explained by the theoretical results that are obtained with the impurity Anderson model by combining intra-atomic multiplet coupling with solid-state hybridization between the Pr 4f and 0 2p states. For 3d XPS the main spectral structures are caused by the hybridization efFect, while for 4d XPS the interplay between the multiplet coupling and the hybridization is essential.

LiCoO& can be vie~ed as the end member of the Li-doped Li"Co, "0, system. It was suggested that this system exhibits a transition from high-spin Co ions in CoO to low-spin Co ions in LiCo02. We present a systematic study of the electronic properties of LiCoOz based on a density-functional calculation. From a good agreement between the theoretical results and the results of various spectroscopies (x-ray photoemission spectroscopy, bremsstrahlung isochromat spectroscopy, and x-ray absorption spectroscopy) we conclude that a one-particle band-structure approach is basically adequate for LiCo02 (while being still controversial for CoO) and we support the conclusion of low-spin Co ions in this cornpound.

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