Kondo scale and coupled fluorescence across the - transition in Ce_0.93Sc_0.07

We present a resonant inelastic x-ray scattering (RIXS) study across the temperature (T ) driven gamma -alpha transition in Ce0.93Sc0.07. RIXS measurements across the Ce M5 edge unambiguously identify the f 1 -> f0 and f 1 -> f2 charge excitations, which provide a quantification of the Ce on-site Coulomb repulsion energy, Uf f . Calculation with a simplified single-impurity Anderson model combined with full multiplet theory reproduces the charge excitations and establishes that the very different Kondo temperatures of the gamma to alpha phase are reflected in RIXS spectra. A systematic T-dependent hysteresis is observed for the f0 final state spectral intensity upon cycling across the gamma -alpha transition. In addition, a fluorescencelike structure also follows the same hysteretic behavior and shows it is directly connected to the weight of the f0 configuration in the ground state. The results indicate that the Ce M-edge RIXS is a reliable quantitative probe of the electronic structure of strongly correlated Ce-based Kondo systems and is sensitive to the emergent Kondo energy scale.