The orbit-lattice interaction of lanthanide ions

The coupling between lattice vibrations and electrons in the partly filled shells of paramagnetic ions is normally presumed to take place via a localized complex consisting of the paramagnetic ion surrounded by its ligands. In such cases the number of parameters is reduced significantly by the use of the superposition model. This model, with some related approximations, has been employed to determine coupling parameters for fluorine, chlorine and oxygen ligands using both experimental and theoretical results. (Author)