Atmospheric reactivity of nitrate radicals: Reaction with peroxy radicals

Abstract The rate constants of the reaction of nitrate and methoxymethyl peroxy, acetonyl peroxy and β-hydroxy (methyl)propylperoxy radicals were measured using laser photolysis coupled with time resolved UV–Visible spectrometry and laser diode spectroscopy over the temperature range 276–356 K, for pressures varying between 280 and 480 Torr and was performed under dry conditions. This work provides the first kinetic data for the reaction of NO 3  + CH 3 OCH 2 O 2 , NO 3  + CH 3 C(O)CH 2 O 2 and NO 3  + (CH 3 ) 2 C(OH)CH 2 O 2 as a function of temperature leading to the following Arrhenius expressions (in cm 3 molecule −1 s −1 ): CH 3 OCH 2 O 2  + NO 3 : k 1 (T) = (1.36 ± 0.70) × 10 −11 exp (-(435 ± 150/T)) CH 3 C(O)CH 2 O 2  + NO 3 : k 2 (T) = (5.47 ± 1.66) × 10 −12 exp (-(282 ± 95/T)) (CH 3 ) 2 C(OH)CH 2 O 2  + NO 3 : k 3 (T) = (1.60 ± 1.27) × 10 −11 exp (-(480 ± 255/T)) These reactions between NO 3 and RO 2 radicals exhibit a low positive temperature dependence over the temperature range 276–356 K indicating that the initiation step involved in the reaction between RO 2 and NO 3 is carried out without an activation barrier. The effect of the peroxy radical structure on the kinetic of its reaction with nitrate radicals is relatively low. We also provide a brief discussion concerning the contribution of this process on the atmospheric elimination of RO 2 in the atmosphere.