Vacuum ultraviolet excitation and emission properties of Pr3+ and Ce3+ in MSO4 (M=Ba, Sr, and Ca) and predicting quantum splitting by Pr3+ in oxides and fluorides - art. no. 195129

The excitation and emission properties of Pr3+ and Ce3+ doped MSO4 (M2+ = C a2+, Sr2+, and Ba2+) were investigated at 293 and 10 K. The lowest 5d level in CaSO4:Pr3+ is located below the 4f(2)[S-1(0)] level resulting in allowe d 4f5d-->4f(2) transitions. In BaSO4 and SrSO4 the lowest 5d level appears above the S-1(0) level and 4f(2)[S-1(0)]-->4f(2) emission is observed. Howe ver, also 4f5d-->4f(2) emission occurs, suggesting the presence of two diff erent Pr centers. The unusual temperature dependence of the emission, point s, however, to a thermal excitation process from the S-1(0) state to the 4f 5d states involving only one site. The internal quantum efficiency of the P -3(0) and D-1(2) emission in BaSO4 is estimated to be 0.1 and 1%, respectiv ely. It will be demonstrated that under host lattice excitation part of the energy is transferred to 4f(2) states with lower energy than the S-1(0) or the 4f5d states. The possibility for quantum splitting to occur in Pr3+ do ped oxides and fluorides will be discussed. Trends observed in the interact ion between the crystal field and the 5d electron of Ce3+, will be applied to predict the energy of the 4f5d states of Pr3+.