The controlled-valence properties of La& "Sr"Fe03 and La& "Sr"Mn03 are studied by means of softx-ray absorption spectroscopy. A comparison between the transition-metal 2p spectra and atomicmultiplet calculations is used to determine the 3d count. The 0 1s spectrum is used to characterize changes in unoccupied states that contain oxygen p character. The results indicate that the holes induced by substitution for both series are located in states of mixed metal 3d-oxygen 2p character. The ground state of LaFe03 is mainly 3d' and becomes 3d'L (where L denotes a ligand hole) in the Lal "Sr"Fe03 series for low Sr concentration. The main component of the ground state of LaMn03 is 3d and becomes a mixture of 3d' and 3d L in the Lal "Sr"Mn03 series. The trends in controlledvalence properties of similar oxides across the transition-metal series can be rationalized within the framework of the Zaanen-Sawatzky-Allen model.

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Using theoretical results from complex rotation calculations and data from experimental photoionization cross sections, the quantum defects, the widths, the oscillator strengths and the shape parameter of Rydberg series of autoionizing 1 P o resonances in helium, excited with synchrotron radiation from the ground state, are reviewed and analysed systematically. The relation of these resonance properties to the propensity rules for radiative and non-radiative transitions in two-electron atoms is established.

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