Luminescence of the SrCl2:Pr crystals under high-energy excitation

The present research was carried out in order to elucidate the mechanisms of energy transfer from the crystal lattice to Pr3+ ions in SrCl2. The luminescence excitation and emission spectra as well as luminescence kinetics of the SrCl2:Pr single crystals containing 0.2 mol% Pr were investigated at 300 and 10 K using the vacuum ultraviolet (VUV) synchrotron radiation. The X-ray excited luminescence spectra of the SrCl2:Pr (CPr=0.2 and 0.5 mol%) and SrCl2:Pr, K (CPr=1.5 mol%; CK=1.5 mol%) crystals were studied at 294 and 80 K. Under optical excitation of the samples in the Pr3+ absorption bands, there were observed five fast ultraviolet emissions assigned to the 4f15d→4f2 transitions, and two long-wave bands corresponding to the f-f transitions. Furthermore, the intrinsic emission bands of SrCl2 were observed at 10 K. The X-ray excited luminescence spectrum of the SrCl2:Pr crystal containing 0.2 mol% Pr, besides intrinsic emission band near 400 nm, has got a long-wave band at about 490 nm of the Pr3+ centers. There were not observed any emission bands of the Pr3+ centers corresponding to the 4f15d-4f2 transitions in the X-ray excited luminescence spectrum of the SrCl2:Pr crystal. The possible mechanisms of energy transfer from the SrCl2 matrix to the Pr3+ centers are discussed.