A luminescence spectroscopy study of scintillation crystals SrI2 doped with Eu2+

Abstract

We report experimental study of luminescent properties of modern scintillation material SrI 2 :Eu 2+ carried out over the temperature range from 9 to 450 K by the means of the ultraviolet and vacuum ultraviolet spectroscopy with a time resolution. Photoluminescence of the Eu 2+ ions at 2.85 eV was studied under both the intracenter and interband excitations, including an X-ray excitation. The bandgap of the SrI 2 crystal has been estimated on the basis of the obtained results. In the temperature range below 100 K the intrinsic luminescence at 3.4 eV was revealed and this emission band was assigned by its properties to the luminescence of selftrapped anionic excitons in SrI 2 . The pronounced manifestation of the effect of multiplication of electronic excitations was revealed in the energy range above 2E g .

A luminescence spectroscopy study of SrI2:Nd3+ single crystals

“…The PL emission spectrum comprises of two broad bands at 2.2 and 2.9 eV (FWHM ¼0.55 and 0.22 eV), respectively. The 2.2 eV band can be caused by crystal hydrates, that arose in the interaction of the SrI 2 surface with the water molecules as it was shown previously for SrI 2 :Eu [16]. Spectroscopic parameters of the low-intensity 2.9 eV band are the same as for the 5d-4f luminescence of Eu 2+ in SrI 2 crystals.…”

“…The concentration of the Nd 3+ impurity ions was chosen to make its luminescence comparable in intensity with the other PL emission bands found previously in SrI 2 crystals [16]. Data on the real structure of the grown crystals of strontium iodide were presented in a previous paper [16]. X-ray diffraction study showed that crystal structure parameters of SrI 2 :Nd crystals have no significant deviations from that of pure SrI 2 presented in Ref.…”

“…Our results (Figs. 4 and 5, Table 1) in combination with the earlier data on SrI 2 :Eu luminescence [16] allow us to make reasonable assumptions about the nature of g 1 …g 5 bands. According to spectroscopic parameters, two of the lower-energy bands g 1 and g 2 are comparable to the PL emission bands from crystal hydrates, which result from the interaction of the SrI 2 surface with water molecules.…”

“…The sizes of the investigated crystals were 6 Â 5 Â 1.5 mm 3 ; the largest surfaces studied were cleaved and parallel. The concentration of the Nd 3+ impurity ions was chosen to make its luminescence comparable in intensity with the other PL emission bands found previously in SrI 2 crystals [16]. Data on the real structure of the grown crystals of strontium iodide were presented in a previous paper [16].…”

“…All details of the obtaining of SrI 2 were described in Refs. [15,16]. The mixture of strontium iodide and 2.5% neodymium iodide was placed to a silica ampoule, which then was evacuated, sealed and placed in a two-zone furnace.…”