title: Pressure and temperature dependence of methyl nitrate formation in the CH3O2 + NO reaction.
abstract: The branching ratio β = k(1b)/k(1a) for the formation of methyl nitrate, CH(3)ONO(2), in the gas-phase CH(3)O(2) + NO reaction, CH(3)O(2) + NO → CH(3)O + NO(2) (1a), CH(3)O(2) + NO → CH(3)ONO(2) (1b), has been determined over the pressure and temperature ranges 50-500 Torr and 223-300 K, respectively, using a turbulent flow reactor coupled with a chemical ionization mass spectrometer. At 298 K, the CH(3)ONO(2) yield has been found to increase linearly with pressure from 0.33 ± 0.16% at 50 Torr to 0.80 ± 0.54% at 500 Torr (errors are 2σ). Decrease of temperature from 300 to 220 K leads to an increase of β by a factor of about 3 in the 100-200 Torr range. These data correspond to a value of β ≈ 1.0 ± 0.7% over the pressure and temperature ranges of the whole troposphere. Atmospheric concentrations of CH(3)ONO(2) roughly estimated using results of this work are in reasonable agreement with those observed in polluted environments and significantly higher compared with measurements in upper troposphere and lower stratosphere.
authors.affiliation: Institut de Combustion, Aérothermique, Réactivité et Environnement (ICARE), CNRS-INSIS 1C Av. de la Recherche Scientifique, 45071 Orléans Cedex 2, France.
authors.forename: Nadezhda
authors.initials: N
authors.lastname: Butkovskaya
authors.forename: Alexandre
authors.initials: A
authors.lastname: Kukui
authors.forename: Georges
authors.initials: G
authors.lastname: Le Bras
mesh_terms: D009566:Nitrates / Q000138:chemical synthesis* / Q000737:chemistry; D009569:Nitric Oxide / Q000737:chemistry*; D010545:Peroxides / Q000737:chemistry*; D011312:Pressure; D013696:Temperature
chemical_list: D009566:Nitrates; D010545:Peroxides; D009569:Nitric Oxide; C421036:methyl nitrate