Formation of hydrated electron and BrO3 radical from laser photolysis of BrO3- aqueous solution

Abstract

Hydrated electron, as well as BrO₃ radical, was observed as one of the products from the laser photolysis of bromate (BrO₃^-) aqueous solution, with an initial quantum yield of (8.0±0.8)×10^-2 determined. The hydrated electron produced can be scavenged rapidly by O₂, OH radical and the parent compound BrO₃^-. The rate constant for the reaction of e_aq^- with BrO₃^- was determined to be 3.0×10⁹ d mol^-1 s^-1 at ionic strength I=0. The BrO₃ radical was observed to have an absorption peak at 315 nm with a molar absorption coefficient of ∽8×10² d mol^-1 cm^-1. In addition, BrO₃ could be also produced from the electron transfer reaction of the sulfate radical (SO₄^-) with BrO₃^-. The radical prefers to dissociate rapidly to form the BrO radical (at a rate of >2.0×10⁵ s^-1). It was also suggested that some of the BrO came from direct photolysis of BrO₃^- solution. Quantum yields of BrO₂ and O from the photolysis of BrO₃^- were determined to be 0.12±0.01 and (7.4±0.6)×10^-3, respectively.