Thallous Ion Centers in Potassium Iodide-Thallium Crystals

Abstract

Absorption, excitation, and emission spectra of KI-Tl crystals have been investigated over the temperature range from 10°K to 300°K. The C band has a temperature sensitive triplet structure and the A band has a temperature sensitive asymmetry. The absorption intensities of the paired thallous ion bands are independent of temperature. Excitation in any band of the paired thallous ion center produces the same single 412 mµ emission band at 10°K. The luminescent processes in the paired thallous ion center are discussed basing on the model of the pseudomolecule composed of two thallous ions. Moreover, the experimental results on the paired thallous ion center in KI-Tl crystals are compared with the previous results on the center in NaI-Tl crystals.