Kinetics of the reaction OH + NO + M → HONO + M as a function of temperature and pressure in the presence of argon, SF 6, and N 2 bath gas

Abstract

The laser photolysis/laser-induced fluorescence technique is used for the direct measurement of the reaction OH + NO + M → HONO + M over the temperature range 298–431 K and over the pressure range 50–400 Torr. Rate constants are measured for the following bath gases: argon, sulfur hexafluoride, and nitrogen. The laser photolysis of nitric acid vapor, HNO 3, at 248 nm is used for the production of OH radicals. The relative concentration of these OH radicals are probed by laser-induced fluorescence. Experiments are performed under pseudo-first-order conditions, where [OH] ⪡ [NO]. Good agreement is observed with previous room temperature measurements. These measurements show that the high pressure limit is far from being reached even at 400 Torr of SF 6.