Luminescence properties of Ce³⁺ and Eu²⁺ in fluorites and apatites

Natural samples of fluorite and apatite from granites, pegmatites, carbonatites and andesitic tuffs were investigated by steady-time spectroscopy to characterize the luminescence properties of Ce³⁺ and Eu²⁺. The luminescence of Ce³⁺ has been clearly seen in fluorite as 320 and 337 or 343 nm bands. In apatites, two distinct bands for two different Ca crystal sites were obtained: 340-380 nm for Ca(1) and 420-450 nm for Ca(2). The luminescence spectra of Eu²⁺ in the fluorite crystals were measured even at for low concentration of this element (0.11 ppm). For Ce³⁺, it has been showed that the crystal field strength depends more on the nature of the ligand than on the Me-ligand distances.