Luminescent properties of Pb2+- and Mn2+- activated CdI2 crystals

The luminescent properties of CdI2, CdI2 : Pb2+, CdI2 : Mn2+, and CdI2 :( Pb2+, Mn2+) crystals have been studied at temperatures from 85 to 295 K under optical and x-ray excitation. Analysis of new and earlier spectroscopic data suggests that the 560-nm luminescence of CdI2 : Pb2+ and CdI2 :( Pb2+, Mn2+) crystals under excitation on the long-wavelength component of the A absorption band of Pb2+ centers is due to Pb2+-bound anion excitons. The 640- to 660-nm emission of these crystals is attributable to a centers. The manganese luminescence in the codoped material originates from both intracenter Mn2+ excitations and a sensitized process due to energy transfer from the host and Pb2+-related centers. The mechanisms of recombination and energy transfer processes in cadmium iodide crystals codoped with Pb2+ and Mn2+ are discussed.