UV absorption spectrum, formation and disappearance of the oxide radical ion O [rad]− in aqueous solution: A pulse radiolysis study

Abstract

The formation and disappearance of O − in oxygen-free aqueous solution at pH 13 has been studied and its spectrum has been re-determined utilizing pulse radiolysis optical measurements in the UV region. The rate constant for the reaction H + OH − is determined to be 2.5 × 10 7 dm 3 mol −1 s −1. A determination of the rate constants for the equilibrium OH + OH - ⇔ O - was not possible; the p K value for this equilibrium was determined to be 11.9. The rate constant for the demerisation O − + O − was measured at 325 nm to be 2 k = 2 × 10 9 dm 3 mol −1 s −1. The absorption spectrum of O − differs significantly from that in the literature below 250 nm.