FLUORESCENCE OF CE3+ IN LIREF(4) (RE=GD,YB)

Optical absorption, emission and excitation spectra of Ce3+-doped LiYb F4 and LiGdF4 crystals are presented. Vibrational structures were obse rved and the vibrational modes were described through Raman spectra. C e3+ and Gd3+ energy level schemes were determined and the influences o f various processes on the Ce3+ luminescence intensity are discussed q ualitatively. The luminescence efficiency of Ce3+ is strongly decrease d by either electron transfer (LiYbF4) or energy migration over the Gd 3+ sublattice to impurities (LiGdF4).