Luminescence of LaBr3: Ce,Hf crystals under photon excitation in the ultraviolet, vacuum ultraviolet, and X-ray ranges

This study has been carried out using synchrotron radiation, time-resolved luminescence ultraviolet and vacuum ultraviolet spectroscopy, optical absorption spectroscopy, and thermal activation spectroscopy. It has been found that, in scintillation spectrometric crystals LaBr3: Ce,Hf characterized by a low hygroscopicity, along with Ce3+ centers in regular lattice sites, there are Ce3+ centers located in the vicinity of the defects of the crystal structure. It has also been found that the studied crystals exhibit photoluminescence (PL) of new point defects responsible for a broad band at wavelengths of 500–600 nm in the PL spectra. The minimum energy of interband transitions in LaBr3 is estimated as Eg ∼ 6.2 eV. The effect of multiplication of electronic excitations has been observed in the range of PL excitation energies higher than 13 eV (more than 2Eg). Thermal activation studies have revealed channels of electronic excitation energy transfer to Ce3+ impurity centers.