Laser-induced luminescence of rare-earth elements in natural fluor-apatites

The luminescence spectra of naturally occurring fluor-apatites containing traces of rare-earth elements have been compared with synthetic fluor-apatites to which single rare-earth elements have been intentionally added. Comparison of the laser-induced spectra obtained after different time delays allows identification of the following luminescence centers: Ce³⁺, Pr³⁺, Nd³⁺, Sm³⁺, Eu³⁺, Tb³⁺, Dy³⁺, Er³⁺, Tm³⁺, Yb³⁺ and possibly Yb²⁺. The technique described here allowed for the first time to detect the luminescence of Pr³⁺, Eu³⁺, Er³⁺, Tm³⁺ and Yb³⁺ in natural apatites. Our results were compared with those obtained by ICP and correspondence was observed between the two methods. Our findings allow non-destructive detection by laser light of the different rare-earth elements in apatite minerals.