Ozone formation in laser flash photolysis of oxoacids and oxoanions of chlorine and bromine

Abstract

The kinetics of ozone formation in the photolysis of oxygen-containing solutions of HClO, ClO^–, ClO^–₂, ClO^–₃, HBrO, BrO^– and BrO^–₃ has been studied by laser flash photolysis and conventional flash photolysis. The usual assumption, that ozone only forms in the reaction of oxygen atoms in the spin-triplet ground state with molecular oxygen: O + O₂→ O₃ subsequent to the primary process [graphic omitted] is found to be valid for solutions at pH ⩽ 10 but not for more strongly alkaline solutions. The rate constants of the reactions of O with O₂ and BrO^–₃ are found to be 4.0 × 10⁹ and 1.5 × 10⁷ dm³ mol^–1 s^–1, respectively. The formation of ozone in strongly alkaline solutions can be accounted for by the additional processes O^–₃+ XO^–_{n– 1}→ O₃+ XO^–_{n– 1} with rate constants in the range 5 × 10⁸ to 1.5 × 10⁹ dm³ mol^–1 s^–1 subsequent to O^–+ O₂⇌ O^–₃ and the primary process [graphic omitted].