Excitation Transfer in the Radiolysis of Solid Hydrocarbons as Studied by ESR Spectroscopy and Product Analysis

Abstract

Abstract The effect of carbon tetrachloride on the radiolysis of isobutane and methylcyclohexane at 77°K is studied by ESR spectroscopy and by product analysis. The yields of solvent radicals from the γ-irradiation of isobutane and methylcyclohexane are not changed by the presence of conventional electron scavengers. This indicates that solvent radicals are not formed by the neutralization of solvent cations with electrons. On the contrary, the yields of solvent radicals decrease remarkably upon the addition of CCl4. Though the yield of propylene from the γ-irradiation of isobutane is not affected by the addition of electron scavengers, it decreases significantly upon the addition of CCl4. Though the decrease in the hydrogen yield in the radiolysis of methylcyclohexane at 77°K upon the addition of electron scavengers is only about 1G-unit, it amounts to more than 3.5G-units upon the addition of CCl4. These characteristic effects of CCl4 can possibly be explained in terms of excitation transfer from the excited solvent molecule to CCl4. A kinetic treatment suggests that its mechanism may be an exciton transfer.