The nature of luminescence centers in NaI:Eu single crystals

Abstract The nature of luminescence centers in NaI:Eu scintillation crystals was studied in a wide excitation energy and temperature ranges. Radio- and photoluminescence spectra and TSL curves were measured for crystals with varied activator concentrations. Two main narrow luminescence bands at 2.8 eV (center I) and 2.6 eV (center II) were found at 10 К. Center I dominates for low Eu concentration ( 2 dopant. Analysis of emission and thermoluminescence features allows justifying the role of anion impurities (oxygen/hydroxyl ions) in formation of activator center II, which is responsible for scintillation efficiency of NaI:Eu crystals at room temperature.