Transient optical absorption as a powerful tool for engineering of lead tungstate scintillators towards faster response

Abstract

Transient optical absorption in the pump and probe configuration and the light-induced transient gratings technique is demonstrated to be a useful tool to support time-resolved photoluminescence spectroscopy in studying the processes responsible for timing properties of self-activated scintillating materials. Lead tungstate (PbWO₄, PWO) doped by lanthanum and yttrium up to high concentrations of 1500 ppm was studied as a prospective scintillator for fast timing applications in high energy physics. Strong localization of nonequilibrium carriers at radiative recombination centers of one type is evidenced, and the observed acceleration of the luminescence decay in heavily doped PWO is interpreted in view of the inequivalent surrounding of the oxyanionic complexes WO₄²⁻ acting as radiative recombination centers together with dipole–dipole interaction between excited complexes at high levels of excitation.