DECAY KINETICS OF CSITL LUMINESCENCE EXCITED IN THE A-ABSORPTION BAND

Luminescence emission, including decay kinetics, has been investigated for CsI:Tl excited in the A absorption band of Tl+, in the temperature range 4-300 K. Three emission bands have been identified and ascribed to transitions from non-equivalent minima on the adiabatic potential surface of the excited state of isolated Tl+ ion centres. Non-radiative energy transfer processes among these minima are distinguished from complex multiexponential decay curves. A theoretical six-level model is constructed, which explains the temperature dependence of the decay times, the ratio of the intensity of the fast component to the intensity of the slow component and, in the region 100-220 K, the steady-state intensities of all three emission bands.