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Atmospheric Fate of a Series of Carbonyl Nitrates: Photolysis Frequencies and OH-Oxidation Rate Constants

Suarez-Bertoa, R., Picquet-Varrault, B., Tamas, W., Pangui, E., Doussin, J-F.
Environmental Science & Technology 2012 v.46 no.22 pp. 12502-12509
air, ambient temperature, atmospheric chemistry, hydroxyl radicals, latitude, methanol, nitrates, oxidation, ozone, photolysis, reactive nitrogen species
Multifunctional organic nitrates are potential NOₓ reservoirs whose atmospheric chemistry is somewhat little known. They could play an important role in the spatial distribution of reactive nitrogen species and consequently in ozone formation and distribution in remote areas. In this work, the rate constants for the reaction with OH radical and the photolysis frequencies of α-nitrooxyacetone, 3-nitrooxy-2-butanone, and 3-methyl-3-nitrooxy-2-butanone have been determined at room temperature at 1000 mbar total pressure of synthetic air. The rate constants for the OH oxidation were measured using the relative rate technique, with methanol as reference compound. The following rate constants were obtained for the reaction with OH: kOH = (6.7 ± 2.5) × 10–¹³ cm³ molecule–¹ s–¹ for α-nitrooxyacetone, (10.6 ± 4.1) × 10–¹³ cm³ molecule–¹ s–¹ for 3-nitrooxy-2-butanone, and (2.6 ± 0.9) × 10–¹³ cm³ molecule–¹ s–¹ for 3-methyl-3-nitrooxy-2-butanone. The corresponding photolysis frequencies extrapolated to typical atmospheric conditions for July first at noon at 40° latitude North were (4.8 ± 0.3) × 10–⁵ s–¹, (5.7 ± 0.3) × 10–⁵ s–¹, and (7.4 ± 0.2) × 10–⁵ s–¹, respectively. The data show that photolysis is a major atmospheric sink for these organic nitrates.