Energy Transfer Mechanism in Pr-Doped SrF$_{2}$ Crystals
Results of investigation of energy transfer mechanism in SrF2 crystals doped with Pr3+ ions are presented. Temperature dependences of 5d-4f and exciton emission in this material under X-ray excitation, and thermostimulated luminescence (TSL) in temperature range 80-300 K are studied. It has been established that in SrF2-Pr3+ crystals the consecutive electron-hole capture mechanism of energy transfer takes place. Also we found that hole centers made a contribution to energy transfer from primary electrons and holes to Pr3+ ions.
Study of Nd2+ absorption in x-irradiated CaF2, SrF2, BaF2 crystals
Abstract The absorption spectra of x-irradiated alkaline-earth fluoride (CaF 2 , SrF 2 , BaF 2 ) crystals doped with Nd 3+ ions have been investigated. X-irradiation results in creating the absorption bands of inter-configuration 4f n –4f n−1 –5 d 1 transitions of Nd 2+ . The charge reduction of the neodymium by irradiation is not temperature-stable and the ions reoxidation (Nd 2+ → Nd 3+ ) occurs under heating to 570 K in CaF 2 , 520 K in SrF 2 and 470 K in BaF 2 .
Exciton 4.29 and 3.65 eV luminescence in CsI:Tl and CsI:Pb
The 4.29 and 3.65 eV emission of CsI:Pb crystals has been studied at 4.2 - 300 K under excitation in the exciton as well as in the lead-induced absorption bands. The results have been compared with those obtained for the corresponding emission of CsI:Tl as well as for the emission of the on-centre and the off-centre self-trapped exciton in a pure CsI crystal. It has been found that, unlike the case in CsI:Tl, in CsI:Pb the 4.29 and 3.65 eV emission is excited not only in the exciton bands but also in the absorption bands of electron impurity centres optically created at 4.2 K together with the centres by photons of 5.1 - 4.0 eV energy. In the latter case this emission is of nature. The optical creation of the centres has been confirmed by luminescence polarization and ESR spectrum measurements.