Resonant inelastic x-ray scattering probing excited states in metallic AmFe₂

Resonant inelastic x-ray scattering (RIXS) is a powerful tool for probing the ground-state electronic configurations of actinide materials. However, in certain metallic uranium compounds, RIXS fails to detect excitations from the ground-state multiplet. This absence is attributed to strong hybridization between uranium 5 f electrons and conduction electrons. In the present study, we extend RIXS investigations to a 16 mu g sample of the metallic compound AmFe2, marking an experiment at the M4,5 edges of a transuranium material. Americium in AmFe2 adopts a trivalent (Am3+) state with a 5 f 6 electronic configuration having a J = 0 ground state, with the 5 f states located approximately 3 eV below EF. The RIXS spectra exhibit well-resolved features that are in good agreement with theory. The localized nature of the 5 f electrons in AmFe2 permits the observation of multiplet excitations despite its metallic character. These observations extend our understanding of RIXS in actinide systems.