Multiplet effects in the Ru L-2,L-3 x-ray-absorption spectra of Ru(IV) andRu(V) compounds

We report combined experimental and theoretical investigations of x-ray abs orption at the Ru-L-2,L-3 and O-K thresholds of the Ru(IV) compounds RuO2 a nd Sr2RuO4 and of the Ru(V) compound Sr4Ru2O9 Significant differences in th e intensity distribution of the t(2g)-related and e(g)-related peaks betwee n the L-3 and the L-2 edges are found, due to the combined effects of 4d sp in-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 fr om 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 divalen t to the trivalent late 3d transition-metal oxides.