Rate measurements of reactions of OH by resonance absorption. Part 6.—Rate constants for OH + NO(+ M)→ HNO2(+ M) over a wide range of temperature and pressure

Abstract

The kinetics of the reaction OH + NO(+ M)→ HNO₂(+ M) have been studied, using flash photolysis to generate OH radicals and time-resolved resonance absorptions to observe the rate of their removal. Effective second-order rate constants, k₁=(– d ln [OH]/dt)/[NO], have been determined at four temperatures, T= 233, 296, 405 and 505 K, and over a range of total gas concentrations: 3.5 × 10¹⁷⩽[M]⩽ 1.6 × 10¹⁹ molecule cm^–3. The kinetics are in the changeover region between third- and second-order. Values of the limiting low pressure rate constants have been determined, and those of the limiting high pressure rate constants estimated, using an interpolation procedure due to Troe. Most of the experiments have been carried out with M = N₂, but some results have been obtained with M = He and Ar.