Direct Observation of Intraionic and Interconfigurational Excitations in an Intermediate-Valence Compound by Raman Spectroscopy

Intraionic spin-orbit-split multiplet levels have been observed by electronic Raman scattering in the intermediate-valence compound EuPd₂{Si}₂$. From the temperature dependence of the Raman peak positions and widths the interconfigurational excitation energy ${E}ₓ$ and an upper limit of the interconfigurational mixing width ${T}f$, respectively, have been obtained. This is the first spectroscopic support for the underlying assumptions of the ionic interconfigurational fluctuation model that has been proposed to describe intermediate valence.