DIFFUSION-KINETIC MODELING OF THE COOPERATIVE EFFECT OF SCAVENGERS ONTHE SCAVENGED YIELD OF THE HYDROXYL RADICAL

The scavenger concentration dependence of the scavenged yield of the h ydroxyl radical produced by the high-energy electron radiolysis of dea erated, and of nitrous oxide saturated, aqueous solutions is modelled using deterministic diffusion-kinetic methods. These calculations prov ide a simple, but valuable, method for estimating the scavenged yield of the hydroxyl radical in a variety of systems containing both hydrox yl radical and hydrated electron scavengers. The scavenging of hydroxy l radicals in an aqueous solution usually can be divided into two comp onents: the yield that would be scavenged by the hydroxyl radical scav engers in the absence of any hydrated electron scavenger and an additi onal contribution arising from the cooperative effect of the hydrated electron scavenger. Hydrated electron scavengers reduce the amount of intraspur e(aq)- + OH reaction and so increase the amount of hydroxyl radical scavenged by a given concentration of hydroxyl radical scaveng er. The yield of scavenged hydroxyl radicals in nitrous oxide solution is not well represented by the sum of the yield of oxide radical anio ns produced by the nitrous oxide scavenging of the hydrated electron a nd the radiation-induced yield of hydroxyl radicals that would be scav enged if the hydrated electron scavenging reaction did not produced hy droxyl radicals. In nitrous oxide solutions a small modification to re flect the increase in intraspur reactions of hydroxyl radicals is nece ssary.