Resonant mixing of widely separated intermediate states and charge transfer at the 4d-4f resonance of La compounds

Soft X-ray emission through the 4d-4f resonance of La is studied with monochromatic photon excitation. Strong mixing of intermediate states over an extended range of up to 21 eV is observed. The emission is resonant and fundamentally different for selective excitation energies. Different intermediate states contribute to the emission of LaAlO3 and LaF3. Inelastic scattering due to charge-transfer excitations from the valence band to 4f and 5p to 4f is observed. Atomic and solid-state effects are treated separately and are in good agreement with our calculations. (orig.)