Stochastic Simulation of the Electron Radiolysis of Water and Aqueous Solutions

Stochastic modeling of the radiolysis of water and of aqueous solutions employing simulated track structures and the independent reaction times methodology is used to investigate the physical and chemical processes underlying observed radiation chemical kinetics. The calculations accurately reproduce both the time dependent yields of eaq- and the scavenging capacity dependence of the (scavenged) yields of eaq-, OH, H2, and H2O2 measured experimentally. The local spatial distribution of eaq- is described by a Gaussian of standard deviation 4.0 nm. This distribution reflects the “thermalization” of the subexcitation electron. The value matches recent experimental estimates but is somewhat wider than predicted in earlier (deterministic) studies. The Gaussian distribution used for H3O+, OH, H, and O has a standard deviation of 0.75 nm, which is of the same order obtained previously using deterministic methods. This distribution is due to the distance traveled between electronic collisions of low-energy (<25 eV) electrons and the fragmentation of the molecular cation, H2O+.