Kinetic studies of diatomic free radicals using mass spectrometry. Part 4.—The Br + OClO and BrO + ClO reactions

Abstract

In a kinetic study of the reaction of ground state Br ²P bromine atoms with chlorine dioxide, it has proved possible to determine not only the rate constant k_–1a for the primary reaction, but also the rate constants k_1a, k_1b, for the various reactions of ClO with BrO radicals via different channels (1a) and (1b). The rate constants (cm³ molecule^–1 s^–1 at 298 K; error = 1.5σ) were as follows: [graphic omitted] The reaction kinetics were studied in a flow system using collision-free sampling of free radicals and stable molecules to a mass spectrometer. The thermochemistry and reaction kinetics of the XO + XO reactions (X = Cl, Br) are discussed. The ClO + ClO, BrO + BrO and BrO + ClO reactions are all thought to occur via related free radical channels, XO + XO ⇌ X + XOO. In addition, the ClO + ClO and BrO + ClO reactions occur through a similar and parallel channel, XO + XO ⇌ X + OXO.