Generation of Color Center Precursors in Alkali Halides by Electrolysis

Abstract

Two types of imperfections (designated as color center precursors) are created in NaCl crystals when they are subjected to electrolysis. Both of these types are present in a crystal not colored by the electrolysis and lead upon irradiation by x-rays to the development of temporary color centers in much larger numbers than are ordinarily produced and to permanent centers in about the same numbers as result when a crystal is directly colored by electrolysis. In crystals colored directly by electrolysis, only the former type of precursor is present. The properties of crystals containing precursors and of those containing color centers derived from precursors have been studied and compared with those of crystals in the other previously known states. A proposal regarding the nature of the second type of precursor is presented.