Cubic and tetragonal Ce3+ ions in strontium fluoride

Abstract

Optical absorption spectra in the vacuum ultraviolet region and high resolutionemission and absorption spectra in the ultraviolet region for cubic and tetragonalCe3+ centresin SrF2 crystals were measured. Cubic centres are characterized by a33 250 cm−1 zero-phonon line and a sharp phonon line spaced from the zero-phonon line by410 cm−1. The decay times of cubic and tetragonal centre luminescences are 32 ns.Comparison of cubic and tetragonal spectra allows us to establish theinfluence of charge compensating interstitial fluorine ions on f and d levels ofCe3+ ions.Non-empirical Hartree–Fock calculations for Ce states in molecular clusters ofalkaline-earth fluorides were performed. To make the calculated transitionscoincide with the experimental ones one needs to take into account a shift ofCe3+ andinterstitial F− towards each other by 10% of the initial distance.