Role of inter- and intraconfigurational transitions of Pr3+ ion in nonequilibrium carrier relaxation in garnet-type scintillators

Abstract Transient optical absorption induced by selective photoexcitation is exploited for a subpicosecond study of the electronic excitation relaxation in Pr3+ acting as an activator ion in garnet-type scintillating materials. Both intra- and interconfigurational (4f2–4f15d1) channels are shown to be important. The latter one limits the rate of population of the emitting level of Pr3+ ion and, consequently, the luminescence rise time. The relaxation time of nonequilibrium carriers to the radiating level of 4f15d1 configuration after selective excitation of Pr3+ ion to higher excited levels is found to be ~4 ps. The energies of the Pr3+ levels involved in the excitation relaxation are estimated in (Lu–Y)3Al5O12:Pr. The obtained results show that the relaxation rate might be decreased by engineering of the crystal field in the vicinity of activator ion.