Spectroscopic properties of Pr3+ ions in a PbWO4 single crystal

Site-selective fluorescence laser spectroscopy of Pr (3+) ions in lead tungstate single crystal were investigated at temperatures from 10 to 300 K. The site-selective emission spectra and fluorescence decays from the (3)P J ( J = 0, 1, 2) and (1)D 2 states were analyzed. The (3)P J ( J = 0, 1, 2) level shows its predominantly radioactive character with the typical greenish-blue luminescence ascribed to (3)P J transition. The emission from the (1)D 2 level is only observed when this level is directly excited. The decay kinetic of the (1)D 2 level was measured under site-selective excitation and discussed in terms of cross-relaxation. The up-conversion emission from levels (3)P 1 and (3)P 0 following excitation of the (1)D 2 state was observed in the PbWO 4 crystal between 10 and 300 K. The main up-conversion mechanism, together with the understanding the quenching of the (1)D 2 fluorescence in this Pr (3+) heavily doped PbWO 4 were discussed. The presence of the complex structures of the emission spectra and different decay profiles indicate that several processes contribute to the quenching of the (1)D 2 fluorescence of Pr (3+) ions. It was found that the up-conversion fluorescence intensity had a quadratic dependence on the laser input power. The temporal behavior of the up converted emission indicates that an energy-transfer up-conversion is the dominant process.