Formation of Colour Centres in Undeformed and Deformed NaCl

Abstract

Abstract Rates of F‐centre formation and absorption spectra after soft and hard X‐irradiation and after subsequent bleaching were studied. Two stages of colouration are found. During the first stage, F‐centres are formed from vacancies present in the crystal prior to irradiation. The second stage during soft irradiation is attributed to the formation of F‐centres by a bulk mechanism; the second stage during hard irradiation, which is significant only in deformed crystals, is attribiuted to the formation of F‐centres from vacancy clusters generated by deformation.