Probing electron correlation, charge transfer, and Coster-Kronig transitions at the3dand4dthresholds of Nd by resonant inelastic scattering

Abstract

Soft x-ray emission near the 3d-4f and 4d-4f thresholds of Nd{sub 2}O{sub 3} is studied with monochromatic synchrotron radiation excitation. At excitation energies above the M{sub IV} threshold, we observe Coster-Kronig enhanced fluorescence from the refill of the 3d hole via the 5p and 4f channel. Fluorescence occurs mainly due to transitions in which charge-transfer provides additional 4f electrons. Resonant inelastic scattering dominates the emission process and we observe two energy loss features at 2.3 and 21 eV, which are due to net transitions within the 4f shell (4f{sup 3}{r_arrow}4f{sup 3}) and 5p{sup 6}4f{sup 3}{r_arrow}5p{sup 5}4f{sup 4}, respectively. The emission spectra resulting from excitations at various energies through the 3d and 4d thresholds were compared and a number of differences were found. Our atomic calculations are in excellent agreement with the experimental results indicating strong localization and a low degree of correlation of the 4f electrons. {copyright} {ital 1999} {ital The American Physical Society}