Transient optical absorption and luminescence in APb2Cl5 (A = K, Rb) crystals

Abstract

This paper reports on a study of transient optical absorption and pulsed cathodoluminescence in APb2Cl5 (A = K, Rb) in the visible and ultraviolet spectral regions. The measurements performed by absorption optical spectroscopy with nanosecond time resolution showed the transient optical absorption of APb2Cl5 to derive from optical transitions in hole centers, and that the optical density relaxation kinetics is mediated by interdefect tunneling recombination in complementary pairs which involves Frenkel defects on the cation sublattice and self-trapped carriers. The slow components in the transient optical absorption decay kinetics, with characteristic times ranging from a few ms to seconds, have been assigned to diffusion-mediated annihilation of interstitial atoms with alkali metal vacancies. The mechanisms underlying creation and relaxation of the short-lived Frenkel defects on the cation sublattice and self-trapped carriers have been analyzed. © Pleiades Publishing, Ltd., 2009.