Кoнцeнтpaциoнныe зaбиcимocти paдиoлизa бинapныx cиcтeм пpи кocвeннoм дeйcтвии излyчeния пo мeчaнизмy c yчacтиeм иoнныx пap

Abstract

A quantitative theory has been devised for the description of concentration dependence in the case when indirect action of radiation occurs via an ion pair mechanism. The resulting expression for the yield of donor decomposition ( G D ) vs. scavenger concentration ( c s ) cannot be integrated mathematically. The results of numerical integration by electronic computing show three different regions of concentration dependence. The proposed approximations, which describe G D = f( c s ) rather accurately, lead to a square-root dependence for the first region, for the second region the dependence is approximately linear and for the third it is exponential. Inequalities have been obtained which determine approximate bounds of every region in terms of microscopic constants. The comparison of this theory with experimental data on radiolysis of cyclohexane with N 2O and CCl 4 as scavengers shows a good agreement between theory and experiments. It has been shown that parameters which quantitatively characterize the dependences obtained are ( G 0/ G) extrap and ξ′ = 1,08(k s r 0 3/αD) , where ( G 0/ G) extrap is the value of the intercept, obtained by extrapolation of concentration dependence to c s = 0; D, the diffusion constant of charges in ion pairs, D = D + + D −; α, the Onsager radius; r 0 , the average initial separation between components of ion pairs; and k s , the rate constant of the reaction between ion pair component and acceptor molecule.