Spectral-kinetics properties of activator emission centers in CsI:Eu

It has been found that only three types of emission centers are responsible for bands at 2.69, 2.78 and 2.67 eV in CsI:Eu crystals grown in vacuum. Within the framework of a suggested model a single dipole Eu2+-vc− is responsible for 2.69 eV band, a two-dipole cluster 2(Eu2+-vc−) for 2.78 eV band and a three-dipole cluster 3(Eu2+-vc−) for 2.67 eV band. The emission at 2.69 and 2.67 eV decays exponentially with time constant 0.42 and 0.9 μs, respectively. The decay kinetics of the emission at 2.78 eV has two exponential components with time constant 0.15 and 0.51 μs. It has been experimentally ascertained that the single dipole, two-dipole and three dipole clusters exist at Eu concentration less than 0.01 mass%; from 0.005 to 0.03 mass% and more than 0.03 mass%, respectively.