Density dependence of the “escape” yield of hydrated electrons in the low-LET radiolysis of supercritical water at 400 °C

Abstract

The “spur lifetime” (τ_s) in the low-linear energy transfer (LET) radiolysis of supercritical water (SCW) at 400 °C has been determined as a function of water density by using a simple model of energy deposition initially in spurs, followed by the random diffusion (Brownian motion) of the species formed until spur expansion is complete. The values of τ_s are found to decrease from ∼5.0 × 10⁻⁶ to 5.0 × 10⁻⁸ s over the density range from 0.15 to 0.6 g cm⁻³. Using Monte-Carlo simulations, our calculated density dependence of the “escape” hydrated electron (e_aq⁻) yield (i.e., at time τ_s) reproduces fairly well Bartels and co-workers' scavenged e_aq⁻ yield data, suggesting that these data may have been measured at times close to τ_s.