Multiplet effects in the Ru L2,3 x-ray-absorption spectra of Ru(IV) and Ru(V) compounds

We report combined experimental and theoretical investigations of x-ray absorption at the Ru-L-2,L-3 and O-K thresholds of the Ru(IV) compounds RuO2 and Sr2RuO4 and of the Ru(V) compound Sr4Ru2O9 Significant differences in the intensity distribution of the t(2g)-related and e(g)-related peaks between the L-3 and the L-2 edges are found, due to the combined effects of 4d spin-orbit coupling and the interelectronic Coulomb interaction described by the Slater integrals. The observed spectral features can be well reproduced by crystal-field-multiplet calculations. With increasing the Ru valence from TV to V, the spectra are shifted by congruent to 1.5 eV to higher energy at the Ru-L-2,L-3 edges and congruent to 1.0 eV to lower energy at the O-K edge, which is of the same order of magnitude as on going from the divalent to the trivalent late 3d transition-metal oxides.