TRACK STRUCTURE SIMULATION AND DETERMINATION OF PRODUCT YIELDS IN THEELECTRON RADIOLYSIS OF WATER CONTAINING VARIOUS SOLUTES

Knowledge of time- and concentration-dependent yields of various radic als and molecular products from irradiation of aqueous solutions conta ining different solutes is important for microdosimetry and the biolog ical modelling of radiation effects. These yields are often calculated from assumptions regarding the initial spatial distributions of the r adical species. The Monte Carlo code, OREC, is used to calculate event -by-event the transport and energy loss of a primary electron and all of the secondaries in liquid water, thus generating the complete track structure. The formation of radicals and molecular species along the track is then computed to obtain the initial spatial distributions fro m the transport calculation itself. The code further follows the inter actions of the species and any available solutes through recombination and molecular product formation. The code yields the spatial distribu tions of all radical species as functions of time and logs the formati on of all molecular products. The code has successfully modelled the t ime-dependent yields of e-aq and OH in the radiolysis of pure water, t he Fricke G value for tritium beta rays, and the yields from X irradia tion of aqueous solutions of glycylglycine. In this paper, the results of the present calculations are compared with recent experimental dat a on the time- and concentration-dependent yields of various species ( e.g. e(aq)-, OH, H-2 H2O2, H) for electrons in pure water and in the p resence of different scavenging solutes, including CH3Cl, HCOOH, Br-, and NO2-. Calculated yields of radical species and molecular products are presented and compared with these experimental data and with resul ts from phenomenological models of others.