title: Photochemical Aging of α-pinene and β-pinene Secondary Organic Aerosol formed from Nitrate Radical Oxidation.
abstract: The nitrate radical (NO3) is the dominant nighttime oxidant in most urban and rural environments and reacts rapidly with biogenic volatile organic compounds to form secondary organic aerosol (SOA) and organic nitrates (ON). Here, we study the formation of SOA and ON from the NO3 oxidation of two monoterpenes (α-pinene and β-pinene) and investigate how they evolve during photochemical aging. High SOA mass loadings are produced in the NO3+β-pinene reaction, during which we detected 41 highly oxygenated gas- and particle-phase ON possessing 4 to 9 oxygen atoms. The fraction of particle-phase ON in the β-pinene SOA remains fairly constant during photochemical aging. In contrast to the NO3+β-pinene reaction, low SOA mass loadings are produced during the NO3+α-pinene reaction, during which only 5 highly oxygenated gas- and particle-phase ON are detected. The majority of the particle-phase ON evaporates from the α-pinene SOA during photochemical aging, thus exhibiting a drastically different behavior from that of β-pinene SOA. Our results indicate that nighttime ON formed by NO3+monoterpene chemistry can serve as either permanent or temporary NOx sinks depending on the monoterpene precursor.
authors.affiliation: School of Chemical and Biomolecular Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.
authors.forename: Theodora
authors.initials: T
authors.lastname: Nah
authors.affiliation: School of Chemical and Biomolecular Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.
authors.forename: Javier
authors.initials: J
authors.lastname: Sanchez
authors.affiliation: School of Chemical and Biomolecular Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Boyd
authors.affiliation: School of Chemical and Biomolecular Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.|School of Earth and Atmospheric Sciences, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.
authors.forename: Nga Lee
authors.initials: NL
authors.lastname: Ng
mesh_terms: D000336:Aerosols / Q000737:chemistry*; D000393:Air Pollutants / Q000737:chemistry*; D000081008:Bicyclic Monoterpenes; D001643:Bridged Bicyclo Compounds / Q000737:chemistry*; D039821:Monoterpenes / Q000737:chemistry*; D009566:Nitrates / Q000737:chemistry*; D055549:Volatile Organic Compounds / Q000737:chemistry
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D000081008:Bicyclic Monoterpenes; D001643:Bridged Bicyclo Compounds; D039821:Monoterpenes; D009566:Nitrates; D055549:Volatile Organic Compounds; C010789:beta-pinene; C005451:alpha-pinene