Luminescence of KI Containing ns² Configuration Ions under Excitation by Exciton Absorption

Abstract

As to KI crystals containning Ga⁺, In⁺, Tl⁺ or Sn²⁺ ions, excitations spectra for the A band emission and emission spectra excited by light of the first exciton absorption band were studied, in order to investigate whether energy is transported to these ions due to exciton diffusion. In the case of Ga⁺, In⁺ and Tl⁺ ions, energy transfer from excitons does not take place. In the case of Sn²⁺ ion, the low energy band of the intrinsic luminescence is over lapped with the A absorption band, and consequently nonradiative resonance energy transfer takes place from the emitting state of the intrinsic luminescence, in addition to radiative transfer due to the reabsorption effect. It is concluded that energy transfer from excitons is effective only for the resonance type an energy transport due to exciton diffusion does not occur in alkali halides.