Luminescence characteristics of Tl+ ions co-doped RbCl:Eu2+ crystals

RbCl:Eu2+ single crystals which are co-doped with thallium display characteristic Eu2+ emission around 420 nm and additional emission band at 312 nm with a weak shoulder around 390 nm attributable to centers involving Tl+ ions. Additional excitation and emission bands observed in Tl+ doped RbCl:Eu2+ single crystals are attributed to the presence of Eu2+ aggregates and complex centres involving both Eu2+ and Tl+ ions. Inclusion of Tl+ ions in RbCl:Eu2+ crystals is found to enhance the intensity of Eu2+ emission at 420 nm due to an energy transfer from Tl+ → Eu2+ ions.