ENDOR and transferred spin densities of the 4f13ions in fluorides

Abstract

The ENDOR of Tm²⁺ cubic paramagnetic centres in KMgF₃ is investigated. The data on the measurements of the transferred hyperfine interaction (THFI) parameters are compared with the THFI data for Tm²⁺ in CaF₂ and Yb³⁺ in KMgF₃, CaF₂. For the interpretation of the total experimental data a new model in which, along with the covalency, the processes of charge transfer to the empty 5d shell and the processes of excitation of the outer 5p⁶ shell with its successive occupation by the electron of the nearest fluorine shell play an essential role is proposed.