Kinetics of the reaction of HO2 with NO2

Abstract

The reaction of HO₂ with NO₂ has been studied using laser magnetic resonance detection of HO₂ with a discharge‐flow system. The proposed reaction mechanism is HO₂+NO₂+M k_1a→HOONO₂+M, and HO₂+NO₂ k_1b→HONO+O₂. Measurements were made at 300 K over the pressure range 0.5–3 torr. HO₂ concentrations down to 10¹⁰ molecules/cm³ were used to eliminate side reactions. The data were analyzed on the basis of the above mechanism and the results are k_la(M) = (M=He)10.0±2.5, (M=N₂)20.9±5.2,(M=O₂) 15.1±3.8, and (M=NO₂)66±30 in the units 10⁻³² cm⁶/molecule² s and k_lb−15 cm³/molecule⋅s. These results indicate that HOONO₂ is the major product of Reaction (1). This conclusion is in agreement with other recent measurements.