Reaction rates of the hydrated electron with NO2−, NO3−, and hydronium ions as a function of temperature from 125 to 380 °C

Reaction rates were measured for the reaction of the hydrated electron with sodium nitrate, sodium nitrite, and perchloric acid using pulse radiolysis/transient absorption at temperatures up to 380 °C. For nitrate and nitrite, the rates increase as the temperature increases, reach a maximum around 125–200 °C and then decrease. Above 350 °C the rates increase again sharply. The perchloric acid rates strongly increase between 250 and 350 °C, and decrease sharply at 380 °C. We interpret the unusual rate behavior at supercritical temperatures in terms of ion pairing, which eliminates coulombic attraction/repulsion between the reactants.