Soft X-ray scattering dominates emission near the giant resonance of the rare earth compounds

Inelastic scattering of 4d electrons near the 4d–4f thresholds of Gd 2 O 2 S and Tm 2 O 3 is studied with monochromatic synchrotron radiation excitation. The emission is dominated by inelastic scattering. We observe two energy loss mechanisms, which are 4f inner-shell excitations (4d 10 4f n →4d 9 4f n +1 →4d 10 4f n ) and 5p–4f excitations (4d 10 5p 6 4f n →4d 9 5p 6 4f n +1 →4d 10 5p 5 4f n +1 ). Our atomic calculations are in excellent agreement with the experimental emission spectra indicating strong localization and a low degree of correlation of the 4f electrons. Inelastic scattering can be used to elucidate the relative partial cross sections for the contributing transitions.