Laser magnetic resonance study of the gas phase reactions of OH with CO, NO, and NO2

Abstract

A laser magnetic resonance spectrometer has been used in combination with a discharge-flow system to measure the gas phase reaction rates of the OH radical with CO, NO, and NO2 at 296°K and over a pressure range 0.4–5 torr. For the bimolecular reaction OH + CO → CO2 + H we measure a rate constant, k = 1.56×10−13 cm3/molecule·sec. For the termolecular reactions OH + NO + M → HNO2 + M, M = He, k = 4.0×10−31 cm6/molecule2·sec; M = Ar, k = 4.4×10−31 cm6/molecule2·sec; M = N2, k = 7.8×10−31 cm6/molecule2·sec. For the reaction OH + NO2 + N2 → HNO3 + N2, k = 2.9×10−30 cm6/molecule2·sec. Laser magnetic resonance detection of radicals is shown to be extremely sensitive, linear, and versatile. A complete description of this technique is presented with a discussion of its potential in the study of the reactions of free radicals.