Radiolysis of aqueous solutions with pulsed helium ion beams - 2. Yield ofSO4.- formed by scavenging hydrated electron as a function of S2O82- concentration

Yields of SO4.- in the radiolysis of aqueous (NH4)(2)S2O8 solutions with pu lsed 24 MeV He-4(2+) ion beams were measured in the concentration range fro m 1 x 10(-4) to 1 mol dm(-3). The yield increased with increasing the conce ntration, and it was smaller than that in electron beam pulse radiolysis in the concentration range measured. The results were compared with the repor ted Ge-aq(-) derived from various scavengers. Though the yields agree well for low LET radiations, the result of the present research for He-4 ion bea ms is smaller than the yield determined by a product analysis method. This suggests that once formed SO4.- 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 di ffusion kinetic model supports it qualitatively. (C) 1999 Elsevier Science Ltd. All rights reserved.