The Radiolysis of Aqueous Solutions at High Intensities

the presence of acid), hydrogen atoms, and hydroxyl radicals. These species are produced in localized regions along the track of the incident radiation. These regions of high radical concentrations expand, and while this process is occurring radical-radical reactions take place leading to hydrogen, hydrogen peroxide, and regenerated water, while radical-solute reactions will also occur to an extent depending on the reactivity and concentration of the solute and the state of expansion of the localized regions. Calculations by various workers (3-6) using the free radical theory have been quite successful in explaining many of the aspects of the radiation chemistry of aqueous systems. A point of uncertainty in the calculations has been the necessity to assume rate constants for the free radical reactions and to assume values for the parameters used to describe the heterogeneous distribution of the radicals produced, and their eventual diffusion and reaction. In the present work conditions were used such that intertrack reactions were important and the diffusion of the radicals from their tracks before chemical reaction took place was sufficient so that they may be considered as being produced homogeneously. An important factor in the irradiation procedure was that the radiation was produced in pulses of a duration such that no significant chemical reaction took place during the pulse. Thus at the end of such a pulse a known concentration of radicals was produced the subsequent reactions of which were described mathematically by normal homogeneous kinetics.