Luminescence and spectroscopic properties of Sm2+ and Er3+ doped SrI2

The scintillation and luminescence properties of SrI2:1% Sm2+ and SrI2:1% Er3+ are reported. Single crystals were grown by the vertical Bridgman technique. Broad band Sm2+ 5d-4f emission was observed centered at 750 nm with a radiative lifetime of 1.25 µs. The photoluminescence decay time increases with temperature due to self-absorption. With Er3+ a clear charge transfer band was identified at 295 nm. The spectroscopic properties of Sm2+ and Er3+ are compared with those of Eu2+, Yb2+, Ce3+, and Nd3+ doped in SrI2. The results are combined to construct a diagram with the vacuum referred electron binding energies for all divalent and trivalent lanthanide ions in SrI2 which is fully consistent with the spectroscopic observations.