title: Reactive uptake of NO3, N2O5, NO2, HNO3, and O3 on three types of polycyclic aromatic hydrocarbon surfaces.
abstract: We investigated the reactive uptake of NO3, N2O5, NO2, HNO3, and O3 on three types of solid polycyclic aromatic hydrocarbons (PAHs) using a coated wall flow tube reactor coupled to a chemical ionization mass spectrometer. The PAH surfaces studied were the 4-ring systems pyrene, benz[a]anthracene, and fluoranthene. Reaction of NO3 radicals with all three PAHs was observed to be very fast with the reactive uptake coefficient, gamma, ranging from 0.059 (+0.11/-0.049) for benz[a]anthracene at 273 K to 0.79 (+0.21/-0.67) for pyrene at room temperature. In contrast to the NO3 reactions, reactions of the different PAHs with the other gas-phase species (N2O5, NO2, HNO3, and O3) were at or below the detection limit (gamma <or= 6.6 x 10(-5)) in all cases, illustrating that these reactions are at best slow. For NO3 we also investigated the time dependence of the reactive uptake to determine if the surface-bound PAH molecules were active participants in the reaction (i.e., reactants). Reaction of NO3 on all three PAH surfaces slowed down at 263 K after long NO3 exposure times, suggesting that the PAH molecules were reactants. Additionally, NO2 and HNO3 were identified as major gas-phase products. Our results show that under certain atmospheric conditions, NO3 radicals can be a more important sink for PAHs than NO2, HNO3, N2O5, or O3 and impact tropospheric lifetimes of surface-bound PAHs.
authors.affiliation: Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3.
authors.forename: Simone
authors.initials: S
authors.lastname: Gross
authors.forename: Allan K
authors.initials: AK
authors.lastname: Bertram
mesh_terms: D001272:Atmosphere; D005740:Gases / Q000737:chemistry; D009566:Nitrates / Q000737:chemistry*; D017942:Nitric Acid / Q000737:chemistry*; D009573:Nitrites / Q000737:chemistry*; D009589:Nitrogen Oxides / Q000737:chemistry*; D010126:Ozone / Q000737:chemistry*; D011084:Polycyclic Aromatic Hydrocarbons / Q000737:chemistry*; D011721:Pyrenes / Q000737:chemistry; D013499:Surface Properties
chemical_list: D005740:Gases; D009566:Nitrates; D009573:Nitrites; D009589:Nitrogen Oxides; D011084:Polycyclic Aromatic Hydrocarbons; D011721:Pyrenes; D017942:Nitric Acid; D010126:Ozone; C010125:nitrogen pentoxide; C030984:pyrene