A temperature dependent study of the spin exchange reactions of muonium with O2 and NO in the range 295 to 478 K

The temperature dependence of the gas phase spin exchange reaction rates for muonium collisions with O2 and NO has been measured over the temperature range 295 to 478 K. In both cases the bimolecular rate constant k(T) was found to vary essentially as T1/2, leading to the following temperature independent spin exchange cross sections: σSE(Mu+NO) = (10.5±0.6)×10−16 cm2 and σSE(Mu+O2) = (9.1±0.7)×10−16 cm2. These results are in quantitative agreement with the H+O2 and H+NO results reported by Gordon et al., demonstrating that there is no isotope effect in spin exchange in this temperature range.