Pulse and γ-radiolysis of concentrated perchloric acid solutions
Abstract
Pulse and γ-radiolysis of concentrated perchloric acid solutions has been investigated. Since perchlorate ion is unreactive to the water decomposition products such as eeq–, H and OH, solute decomposition occurs only through the direct effect of radiation. From pulse radiolysis experiments using scavengers, G(ClO4˙)= 0.083 ± 0.01 and G(ClO3˙)= 0.052 ± 0.01 µmol J–1 have been determined. In highly concentrated solutions, two components with transient absorption at 350 and 440 nm are observed. The shorter-wavelength component is attributed to ClO3˙. G(ClO3˙) calculated using ε= 470 m2 mol–1 at the peak is 0.052 µmol J–1, which is consistent with the value determined from scavenger experiments. The longer-wavelength component is detected in perchloric acid solutions with concentration > 10 mol dm–3. This species is tentatively assigned to HClO4+, formed in the direct decomposition of HClO4 molecule. From γ-radiolysis G(ClO3–)= 0.10 ± 0.01 µmol J–1 was determined, and O(3P) is formed together with ClO3–. With G(ClO4˙)= 0.083, G(ClO3˙)= 0.052 and G(ClO3–)= 0.10 µmol J–1 and the reaction scheme proposed in this work, the yields of the final products reported previously can be explained.