THERMOLUMINESCENCE AND PHOTOSTIMULATED LUMINESCENCE OF CALCIUM HALOPHOSPHATE DOPED WITH EU

Calcium halophosphate doped with Eu, Ca-5(PO4)(3)(F, Cl):Eu, was inves tigated by thermoluminescence, photoluminescence, and diffuse reflecti on in order to characterize the optical storage properties of this mat erial. The different photoluminescence emission spectra of Eu3+ and Eu 2+ in Ca-5(PO4)(3)(F, Cl) were observed and in addition, the decay tim es of the corresponding transitions were determined. By application of X-ray radiation an efficient conversion of the dopant charge state fr om Eu3+ to Eu2+ could be achieved. The luminescence of Eu2+ can be opt ically stimulated with photon energies of 1.9 eV which is lower than t he required energy for the direct excitation of the Eu2+ transition.