Characteristics of the Thallous Dimer Center in Sodium Iodide

Abstract

An investigation of some of the characteristics of the thallous double center (dimer) in NaI: Tl was carried out over the temperature range 15 to 300\ifmmode^\circ\else\textdegree\fi{}K and for thallium concentrations of 0.08 to 1.01 mole% Tl. A measurement of the lifetime of the dimer excited state resulted in a value of 7 nsec as an upper limit. The decay time is independent of temperature and thallium concentration for the ranges investigated. A symmetry determination yielded as the dimer center a $〈100〉$ cube-edge direction. The radiation model of the dimer center is discussed.