STOCHASTIC SIMULATION OF THE ELECTRON RADIOLYSIS OF WATER AND AQUEOUS-SOLUTIONS

Stochastic modeling of the radiolysis of water and of aqueous solution s employing simulated track structures and the independent reaction ti mes methodology is used to investigate the physical and chemical proce sses underlying observed radiation chemical kinetics. The calculations accurately reproduce both the time dependent yields of e(aq)(-) and t he scavenging capacity dependence of the (scavenged) yields of e(aq)(- ), OH, H-2, and H2O2 measured experimentally. The local spatial distri bution of e(aq)(-) is described by a Gaussian of standard deviation 4. 0 nm. This distribution reflects the ''thermalization'' of the subexci tation electron. The value matches recent experimental estimates but i s somewhat wider than predicted in earlier (deterministic) studies. Th e Gaussian distribution used for H3O+, OH, H, and O has a standard dev iation of 0.75 nm, which is of the same order obtained previously usin g deterministic methods. This distribution is due to the distance trav eled between electronic collisions of low-energy (<25 eV) electrons an d the fragmentation of the molecular cation, H2O+.