Determination of the Rate Constants for the Gas Phase Reactions of NO3 with H, OH and HO2 Radicals at 298 K

The reactions of NO3 with H (1), OH (2) and HO2 (3) radicals have been investigated at 298 K using a discharge flow system equipped with mass spectrometric and fluorescence detectors. The rate constants k(1) and k(2) were determined by numerical modeling of experimental [OH] profiles from reactions (1) and (2). In the reaction of NO3 with HO2 (3) the growth and decay of [OH] as well as the decay of [HO2] were measured. Comparison of these two profiles provided evidence for two different reaction paths (3a) and (3b), for which the rate constants were determined by numerical modeling. Experiments carried out in a wide range of reactant concentrations yielded in units of cm3 molecule−1 s−1 k(1) = (0.94 ± 0.2) · 10−10, k(2) = (1.22 ±0.35) · 10−11, k(3a) = (2.5 ± 0.7) · 10−12, and k(3b) = (1.9 ± 0.8) · 10−12. The results are compared with literature data.