Temperature dependence of Frenkel-pair production fromF-aggregate center destruction

Measurements of the radiation destruction of $F$-aggregate centers between 70 and 250 K have yielded values for the primary-Frenkel-pair production efficiencies in NaCl, RbCl, KBr, and KI as a function of temperature. The so far unexplained increase in production efficiency with temperature originally demonstrated for KCl has also been observed in these materials, and has been found to be only a slight function of the species of cation, but a strong function of anion species making up the alkali halides. The apparent agreement between the activation energy obtained for KBr in these measurements and pulsed radiolysis measurements is discussed, and a problem concerning previously proposed explanations is indicated. In addition, the very strong temperature dependence previously observed in KI and attributed to the disappearance of luminescence has been observed and correlated with the thermal quenching of the 3.31-eV component of the fundamental luminescence.