Potential-Barrier Effects in Photoabsorption. II. Interpretation of Photoabsorption Resonances in Lanthanide Metals at the4d-Electron Threshold

The resonances in the photoabsorption spectra of the lanthanides near the $4d$ absorption edge are interpreted as transitions of the type $4f^{10}4f^N\to 4d^{9}4f^{N+1}$. Calculations of the $4d^{9}4f^{N+1}$ energy levels and relative $\mathrm{gf}$ values for these transitions are shown to be in good agreement with the observed absorption spectra. The assumption that the lanthanides occur in trivalent form (with the exception of Eu and Yb) in the metallic solid state is confirmed by these results.