Rate Measurements on OH + NO + M and OH + NO2 + M

Abstract

Measurements of the termolecular rate constants for $\mathrm{OH+NO+M}\to {\mathrm{NHO}}_2+\mathrm{M}{\mathrm{(k}}_1)$ and ${\mathrm{OH+NO}}_2+\mathrm{M}\to {\mathrm{HNO}}_3+\mathrm{M}{\mathrm{(k}}_2)$ in a fast flow reactor with ESR detection of OH decay are reported. The method was to add large excesses of either NO or NO₂ to OH generated by the reaction ${\mathrm{H+NO}}_2\to \mathrm{NO+OH}$ so that pseudo‐first‐order OH decay resulted. Experiments over a pressure range of 0.5–5 torr for M = He gave the results k₁ = 4.7, 2.9, and 1.3×10¹⁷, and k₂=7.3, 5.7, and ${\text{2.1× 10}}^{17}\hspace{0.17em}{\mathrm{cm}}^6\hspace{0.17em}{\mathrm{mole}}^{\text{−2}}·{\sec }^{\text{−1}}$ at 273, 298, and 395°K, respectively. Data at 298°K for M = Ar were about a factor of 2 lower for both reactions.