Yields of H2 and hydrated electrons in low-LET radiolysis of water determined by Monte Carlo track chemistry simulations using phenol/N2O aqueous solutions up to 350 °C

The effect of temperature on the yields of H 2 and hydrated electrons (e aq − ) in the low linear energy transfer (LET) radiolysis of liquid water has been modeled by Monte Carlo track chemistry simulations using phenol/N 2 O aqueous solutions from 25 up to 350 °C. N 2 O was used to scavenge e aq − and H&z.rad; atoms formed in spurs giving N 2 as a product. The primary aim of this work is to elucidate the main factors that account for the anomalous increase in the H 2 yield with temperature. Comparing our calculated H 2 and N 2 yields with experiments led us to re-evaluate certain parameters involved in radiolysis, such as the H − /H 2 O dissociative electron attachment (DEA) cross section and its variation with temperature. Most importantly, we found that the prompt DEA process largely dominates the temperature dependence of the primary yield of H 2 over most of the temperature range considered. Unlike what has been proposed by some authors in the literature, our simulations showed that the oxidation of water by H&z.rad; atoms contributes only ∼12% of the total g (H 2 ) at 350 °C and is thus insufficient to quantitatively explain, by itself, the increase in g (H 2 ) with temperature that is observed experimentally above 200 °C. The effect of temperature on the yields of H 2 and hydrated electrons in the low linear energy transfer radiolysis of water has been modeled by Monte Carlo track chemistry simulations using phenol/N 2 O aqueous solutions from 25 up to 350 °C.