Reactions of HO2 with NO and NO2 studied by mid-infrared laser magnetic resonance
Abstract
The technique of mid-infrared laser magnetic resonance spectroscopy combined with a discharge-flow system has been used to study reactions of the HO2 radical at total pressures up to 13 Torr, corresponding to conditions in the middle stratosphere.
The validity of the technique was confirmed by the determination of a rate coefficient of (8.5 ± 1.3)× 10–12 cm3 molec–1 s–1 at 297 K for the reaction HO2+ NO → OH + NO2 in excellent agreement with previous studies. The reaction HO2+ NO2+ M → HO2NO2+ M was also studied. For M = He, the rate coefficient is (6.0 ± 1.5)× 10–32 cm6 molec–2 s–1 at 297 K, while the data for M = Ar were fitted by the expression 1.24 × 10–31(T/300)–2.37±0.16 cm6 molec–2 s–1 between 275 and 326 K.