Exciton‐Induced Colour Centre Growth in KBr and KI Crystals at 5 °K

Colour centres were created in KBr and KI at 5 °K by ultraviolet irradiation, corresponding to the exciton absorption region, and traced by luminescence methods. In KBr the Frenkel defects (I‐centres) are observed in thermal glow curves, created as a result of the fundamental reaction proposed by Pooley. In KI they are not observed, but F‐, F′‐, and VK‐centres were found in photostimulated luminescence. The dissociation of the migrating excitons at structure defects existing in crystals before irradiation seems to be important at the initial coloration stages in KI.