An interpretation of the spectra of bivalent rare-earth ions in crystals

Abstract

The 4f^{n– 1}5d configuration behaves according to a J₁γ_n coupling scheme in crystals, where J₁ is the total angular momentum of a Russell–Saunders term derived from 4f^{n– 1} and J₁γ_n is a state of the 5d electron in the crystal field. The spectra of several ions in alkaline earth fluorides and of Sm²⁺ in alkali halides correspond to 4fⁿ→J₁γ_n transitions with Δ, the separation between γ₃ and γ₅ in O_h, and E_fd, a coulombic parameter, both pointing to a similarity of effects on passing through each half of the series of rare earths.