Crystal field, ligand polarization and electron correlation third order contributions to the f↔f transition probabilities

Abstract

A method for analysis of the influence of electron correlation inside the rare earth ion and polarization of ligands on the f↔f transition probabilities is presented. The approach is formulated by means of double perturbation theory and in terms of effective tensor operators. The detailed discussion of the structure of the third order contributions to the line strength is performed. The main attention is directed to the new term which represents both mechanisms simultaneously. The values of some third order contributions for [³ P]₀-[³ H]₄ and [³ P]₀-[³ F]₄ electric dipole transitions in Pr⁺³: LaCl₃ are calculated.