Radiolysis of aqueous solutions with pulsed helium ion beams -: 2.: Yield of SO.-4 formed by scavenging hydrated electron as a function of S2O2-8 concentration

Yields of SO(4)(.-) in the radiolysis of aqueous (NH(4))(2)S(2)O(8) solutions with pulsed 24 MeV (4)He(2+) ion beams were measured in the concentration range from 1 x 10(-4) to 1 mol dm(-3). The yield increased with increasing the concentration, and it was smaller than that in electron beam pulse radiolysis in the concentration range measured. The results were compared with the reported Ge(aq)(-) derived from various scavengers. Though the yields agree well for low LET radiations, the result of the present research for (4)He ion beams is smaller than the yield determined by a product analysis method. This suggests that once formed SO(4)(.-) disappears by the intra-track reactions and that this effect is more important in ion beam radiolysis because of more dense production of the initial species. Simulation by the deterministic diffusion kinetic model supports it qualitatively. (C) 1999 Elsevier Science Ltd. All rights reserved.