Excitation of Luminescence from KI:Tl at 5°K

Emission and excitation spectra of single and double thallous ion fluorescence are measured in KI:Tl 0.06 mole %) at 5°K. Spectra are also measured of the emission during x irradiation, of the emission stimulated after irradiation, and of the phosphorescence after irradiation. There are differences between the stimulated emission, which is entirely the result of recombination of electrons and holes, and the x-ray-induced emission. Two possible interpretations of the differences are discussed and the suggestion favored that hot electrons produced in the radiation shower excite optically available states of the thallium ion.