Upconversion luminescence and hypersensitive transitions of Pr3+-doped calcium aluminosilicate glasses

We present a detailed spectroscopic study of photoluminescence in calcium aluminosilicate glasses doped with different concentrations of Pr3+ (0.2, 0.5, 1.0 and 2.0 wt%). Optical transitions for the levels H43→P0,1,23; I61; D21; G41; 3F2,3,4 and H63 have been observed using UV-Vis-NIR spectroscopy at room temperature. Emissions from levels P03 and D21 were detected and curves deviate from exponential behavior. Upconversion to UV was also observed when the samples were excited in the 3Pj level, populating 4f5d upper level - via energy transfer upconversion and/or excited state absorption - which decays emitting UV light. In addition, the unusual variation of the peak intensities of transitions P03→F23 and P03→F43 suggests they are hypersensitive, although the 3P0→3F4 electronic transition does not entirely obey all the classic selection rules.