Intracenter processes induced by electron beam and 337 nm laser light in CsI:Tl

Investigated are the spectral-kinetic properties of the activator luminescence excited in CsI:Tl crystal by a pulsed electron beam and by a pulsed nitrogen laser at λ = 337.1 nm, that corresponds to the long-wave decline of the A-absorption band. It is found that the decay kinetics of 2.6 and 2.25 eV luminescence bands excited by an electron beam at 80 K is mono-exponential with the time constants τ = 4 μs and τ = 13 μs, respectively. The decay kinetics of each from the luminescence bands under the laser excitation is bi-exponential due to the presence of one more component with time constant τ = 900 ns. This sub-microsecond component dominates in the bi-exponential kinetics, and the value of its time constant is determined by the time of the electron transfer from the metastable Ψ sub-level of the excited 6²P_3/2 state to the ground 6²P_1/2 state of Tl⁰ center. Phonon-assisted processes causing population of the radiative states of Tl⁺ centers responsible for 3.0, 2.25 and 2.6 eV luminescence bands are discussed in detail.