Study with Analytical Equations of Absorption Spectra Containing Interference Dips in Fluoride Glasses Doped with Cr3

The optical absorption of Cr3+-doped fluoride glasses has been investigated. The lowest energy absorption band 4A2 → 4T2 shows distinct interference dips due to spin–orbit coupling between 4T2, 2E and 2T1 excited states. The dips were analyzed using an analytical method proposed by Bussiere et al. (J. Phys. Chem. A 2003, 107, 1258) based on coupled potential energy surfaces. Then a theoretical crystal-field analysis based on the Racah tensor algebraic method was carried on Cr3+ ions occupying octahedral site symmetry in the fluoride glasses. Satisfactory correlations were obtained between the experimental and calculated energy levels. The fitting of the interference dips also provided a measure of the spin–orbit coupling constant for Cr3+ in fluoride glasses, intermediate between the theoretical value calculated for a fluoride crystal and the value deduced from Racah parameters.