Selective laser spectroscopy of a highly dispersed Bi4Ge3O12 scintillator doped with Pr3+ ions

Abstract

The optical properties of a highly dispersed bismuth orthogermanate powder Bi4Ge3O12: Pr3+ (HDP_BGO: Pr3+) were studied at Т = 300 K. The fluorescence of undoped HDP_BGO under ultraviolet (UV) excitation (λexc = 266 nm) was shown to result from Frenkel excitons (GeO44−, BiO69−). The HDP_BGO fluorescence decay kinetics under UV excitation had a complex decay form similar to that of BGO single crystal and was a sum of four exponentials with lifetimes τ1, 2, 3, 4– 0.16/0.30/0.70/2.7 μs respectively. Two types of Pr3+ ions optical centers with lifetimes of ∼5.0 and 85 μs have been determined in a HDP_BGO: Pr3+. The resonance energy transfer of the electronic excitation from the HDP_BGO to Pr3+ions was identified. The effect of Pr3+ ions on the HDP_BGO fluorescence lifetime reduction from 160 to 35 ns was established.