Spectral intensities of the trivalent lanthanides. Part 2.—An assessment of the vibronic contribution

Abstract

The temperature dependence of the intensities of ƒ↔ƒ spectra is considered. The spectra of glasses of K₁₃[Eu(SiW₁₁O₃₉)₂] and K₁₃[Ho(SiW₁₁O₃₉)₂] have been obtained at 295 and 80 K. From this and other evidence it is concluded that for molecular complexes of the lanthanides in solution or in the solid state, the perturbation causing the intensity is predominantly static. A vibronic mechanism may be important for lanthanide ions in crystals.