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.