Nanosecond pulse radiolysis of aqueous solutions containing proton and hydroxyl radical scavengers

Abstract

The time dependence of G (e + aq ) in the early stages of the radiolysis of water has been investigated using nanosecond pulse techniques by studying the effects of added solutes which remove H 3 O + aq and OH. In pure water G (e aq ) = 3.6 at 7.5 ns and 2.8 at 120 ns after a 5 ns electron pulse. Successive addition of 1 mol OH - /l and 1 mol CH 3 OH/l increased G (e aq ) at the earlier time to 4.45 and 5.05 respectively. 1 mol I - /l had virtually no effect, and 1 mol Cl - /1 only a slight effect, on G (e aq ) in neutral water, and 1 mol HCO 2 /I had no effect at pH 14. From these results it is concluded that (i) G 0 e aq is not less than 5, (ii) G 0 H is close to zero, and (iii) in the expanding spurs e aq + e aq occurs between 10 -8 and 10 -7 s with A G (e aq ) = 0.6, e aq + OH takes place between 10 -9 and 10 -8 s with A G (e aq ) = 0.5, and e aq + H 3 O + aq is predominant between 10 -11 and 10 -9 s, is 80 % complete in 10 -8 s and complete in 10 -7 s with A G (e aq ) = 1.1. Thus the data are in good agreement with the diffusion model and indicate that neither dry charge recombination nor direct excitation of water plays a significant role in the radiolysis of water.