Scavenging of "dry" electrons prior to hydration by azide ions: Effect on the formation of H₂ in the radiolysis of water by ⁶⁰Co γ-rays and tritium β-electrons.

In this study, we use Monte Carlo track chemistry simulations to show that "dry" secondary electrons, precursors of the "hydrated" electron (e<sup>-</sup><sub>aq</sub>), can be scavenged on sub-picosecond time scale prior hydration, by a high concentration (>0.1-1 M) azide ions (N<sub>3</sub><sup>-</sup>) in water irradiated with <sup>60</sup>Co γ-rays and <sup>3</sup>H β-electrons at 25 °C. This is striking result, as N<sub>3</sub><sup>-</sup> known react very slowly e<sup>-</sup><sub>aq</sub>. These processes tend significantly reduce yields H<sub>2</sub> observed experimentally. For both energetic Compton electrons ("linear energy transfer", LET ∼ 0.3 keV/μm), which are generated cobalt-60 γ-rays, (LET 6 our yield results confirm previous simulations, indicated necessity including capture Interestingly, calculations no significant changes scavenging concentrations passing from γ-radiolysis tritium β-radiolysis (<i>i.e.</i>, LET). led us conclusion higher experimentally for compared explained mainly difference radiation structures during chemical stage (>1 ps). The leads more molecular products (H<sub>2</sub> case) radiolysis than γ-radiolysis. Finally, value 0.5 nm was derived reaction distance between “dry” concentrations.