Cubic and tetragonal Ce3+ ions in strontium fluoride

Abstract

Optical absorption spectra in the vacuum ultraviolet, and high resolution emission and absorption spectra in the ultraviolet region of cubic and tetragonal Ce3+ centres in SrF2 crystals were measured. Cubic centres are characterised by the zero phonon line at 33250cm−1 and a sharp phonon line is spaced from the zero phonon line by 410cm−1. The decay times of the luminescence from the cubic or tetragonal centres are equal to 32ns. A comparison of the cubic and tetragonal spectra allows us to determine the influence of the charge compensating interstitial fluorine ion on the f and d levels of the Ce3+ ions.Unrestricted Hartree–Fock calculations of Ce states in molecular clusters of alkaline-earth fluorides were performed. To make the calculated transitions coincide with the experimental one it is necessary to take into account the shift of the Ce3+ and interstitial F− ions toward each other by 10% of initial distance.