Electronic absorption spectra of Fe(III) in some phosphate glasses

Electronic absorption spectra of Fe(III) in some phosphate glasses have been measured at room and near liquid-nitrogen temperatures, in the energy range 11,500–30,000 cm⁻¹. Assuming cubic-field microsymmetry, and taking no account of spin-orbit coupling, it was found that the energies of the five observed bands are accounted for satisfactorily in terms of single values of B, C and Δ using the free-atom representation of the crystal-field theory, provided that a Trees' correction is included. It was found that the simple strong-field representation gives less satisfactory results. The Racah parameters, B and C, were evaluated for Fe(III) in two different phosphate media without a pre-assigned value of the fraction C/B and an empirical value of C/B = 3.60 was determined and applied to other data in the literature.