Comment on “Heavy ozone in the stratosphere”

It has recently been suggested (Bates [1986]) that the rate constant for the O + O 2 recombination reaction to form ozone should be surprisingly dependent on the isotopic composition of the reactants and products through their symmetry numbers. The argument neglected the fact that isotope exchange and recombination reactions share a common energized collision complex, which can decay by dissociation to products which are isotopically distinct from the original reactants. Proper accounting for this additional exit channel in isotopically labeled O 3 * eliminates this apparent "symmetry number" effect.