Publication Date:
2019-05-13
Description:
The radical terminating, termolecular reaction between OH and NO2 exerts great influence on the NOy / NOx ratio and O3 formation in the atmosphere. Evaluation panels (IUPAC and NASA) recommend rate coefficients for this reaction that disagree by as much as a factor 1.6 at low temperature and pressure. In this work, the title reaction was studied by pulsed laser photolysis-laser induced fluorescence over the pressure range 16–1200 mbar and temperature 217–333 K in N2 bath-gas, with experiments at 295 K (67–333 mbar) for O2. In-situ measurement of NO2 using two optical-absorption set-ups enabled generation of highly precise, accurate rate coefficients in the fall-off pressure range, appropriate for atmospheric conditions. We found, in agreement with previous work, that O2 bath-gas has a lower collision efficiency than N2 with a relative collision efficiency to N2 of 0.74. Using the widely used Troe-type formulation for termolecular reactions we present a new set of parameters with k0(N2) = 2.6 × 10−30 cm6 molecule−2 s−1, k0(O2) = 2.0 × 10−30 cm6 molecule−2 s−1, m = 3.6, k∞ = 6.3 × 10−11 cm3 molecule−1 s−1, Fc = 0.39 and compare our results to previous studies in N2 and O2 bath-gases.
Electronic ISSN:
1680-7375
Topics:
Geosciences