Scintillation properties and self absorption in SrI2:Eu2+

The scintillation properties of pure SrI₂ and SrI₂ doped with 0.5%, 0.86%, 2%, and 5% europium were studied. Different techniques were used to measure γ-ray excited pulse-height and scintillation decay time spectra, and to perform X-ray excited and optically excited emission spectroscopy. Eu²⁺ emission and self-trapped exciton (STE) emission was observed in SrI₂:Eu²⁺ samples. These emissions were studied as a function of temperature, Eu concentration, and sample size. A spectral overlap was observed between Eu²⁺ excitation and emission spectra, which strongly depends on temperature. The light yield, energy resolution and luminescence decay profiles reveal also a strong dependence on temperature, sample size, and Eu concentration. The observations were analyzed and interpreted in terms of two separate models. One model consists of the relation between STE and Eu²⁺ emissions and the other deals with self absorption processes.