Thermal decomposition of γ-irradiated silver malonate

Abstract

The effects of pre-irradiation with γ-rays on the isothermal decomposition kinetics of silver malonate have been studied quantitatively. Such pretreatment reduced the length of the induction period to the onset of reaction and increased the rate of subsequent salt breakdown, which has been shown to proceed by a nucleation-and-growth mechanism. Between 6.5 × 10⁶ and 1.0 × 10⁹ rad, the shapes of the isothermal, fractional-decomposition vs. time curves were unchanged as a result of irradiation and the increase in reaction rate was directly proportional to the γ-ray dose. It is concluded that pre-exposure to ionizing radiation increases the number of nuclei that are active in salt breakdown in direct proportion to the dose to which the sample had previously been exposed. The influence of radiation on the induction period is also discussed; the evidently greater reductions in length, for samples exposed to larger radiation doses, are attributed to radiation damage of the crystal, associated with the presence of radicals detected by an e.s.r. signal.