Rate constants for the reaction OH+NO2+M → HNO3+M under atmospheric conditions

We present rate constants for the title reaction, k1, measured using a pulsed photolysis–laser induced fluorescence technique between 220 and 250 K in 20–250 Torr of N2 and 20–50 Torr of O2. Our measured k1 agree with literature values at low temperatures but show that the current recommendations for atmospheric modeling overestimate k1 by 10–30% in the falloff region below 250 K. The revised values of k1 help to better define the role of NO2 in the stratosphere.