Optical properties of F A and (F 2 )a centres in doped KI

Abstract
Crystals of additively coloured KI doped with lithium or sodium exhibit, after irradiation with F-light, new absorption and emission bands due to associated and perturbed centres. The defects responsible for these bands have been identified using excitation spectra and polarization measurements. Fa(I) and (F2)a centres are found to be present in both KI:Li+ and KI:Na+ crystals. A weak emission in KI: Li+ is ascribed to FB(II) centres. The possibility of using these systems as laser active media is discussed.