Experimental evidence for spatial correlation between F and H centres formed by exciton decay at low temperatures in KBr

Abstract

Optical detection of electron panmagnetic resonance of F-H-centre pairs created by low-temperature w a y irradiation of KBr was performed via the magnetic circular dichroism of the optical absorption (MCDA) whereby cross-relaxation (a) effects between the H and F centres were detected in the MCDA of the F centres.A quantitative analysis of the CR effects yielded d k c t experimental evidence that all F and H centres are spatially correlated after their low-temperamre formation with a separation of four lattice sites along the (110) directions.A theoretical analysis of the CR result yields an estimate of the Fsentre formation time of 2 ps, in agreement with other experimental evidence, and also shows that the F-H separation obtained is the first stable F-H-eentre pair configuration.