title: Efficient Isoprene Secondary Organic Aerosol Formation from a Non-IEPOX Pathway.
abstract: With a large global emission rate and high reactivity, isoprene has a profound effect upon atmospheric chemistry and composition. The atmospheric pathways by which isoprene converts to secondary organic aerosol (SOA) and how anthropogenic pollutants such as nitrogen oxides and sulfur affect this process are subjects of intense research because particles affect Earth's climate and local air quality. In the absence of both nitrogen oxides and reactive aqueous seed particles, we measure SOA mass yields from isoprene photochemical oxidation of up to 15%, which are factors of 2 or more higher than those typically used in coupled chemistry climate models. SOA yield is initially constant with the addition of increasing amounts of nitric oxide (NO) but then sharply decreases for input concentrations above 50 ppbv. Online measurements of aerosol molecular composition show that the fate of second-generation RO2 radicals is key to understanding the efficient SOA formation and the NOx-dependent yields described here and in the literature. These insights allow for improved quantitative estimates of SOA formation in the preindustrial atmosphere and in biogenic-rich regions with limited anthropogenic impacts and suggest that a more-complex representation of NOx-dependent SOA yields may be important in models.
authors.affiliation: Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory Richland, Washington 99352, United States.
authors.forename: Jiumeng
authors.initials: J
authors.lastname: Liu
authors.forename: Emma L
authors.initials: EL
authors.lastname: D'Ambro
authors.forename: Ben H
authors.initials: BH
authors.lastname: Lee
authors.forename: Felipe D
authors.initials: FD
authors.lastname: Lopez-Hilfiker
authors.affiliation: Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory Richland, Washington 99352, United States.
authors.forename: Rahul A
authors.initials: RA
authors.lastname: Zaveri
authors.affiliation: Paulson School of Engineering and Applied Sciences and Department of Chemistry and Chemical Biology, Harvard University , Cambridge, Massachusetts 02138, United States.
authors.forename: Jean C
authors.initials: JC
authors.lastname: Rivera-Rios
authors.affiliation: Paulson School of Engineering and Applied Sciences and Department of Chemistry and Chemical Biology, Harvard University , Cambridge, Massachusetts 02138, United States.
authors.forename: Frank N
authors.initials: FN
authors.lastname: Keutsch
authors.affiliation: Department of Chemistry, University of Helsinki , Helsinki FI-00014, Finland.
authors.forename: Siddharth
authors.initials: S
authors.lastname: Iyer
authors.affiliation: Department of Chemistry, University of Helsinki , Helsinki FI-00014, Finland.
authors.forename: Theo
authors.initials: T
authors.lastname: Kurten
authors.affiliation: Department of Environmental Sciences and Engineering, University of North Carolina , Chapel Hill, North Carolina 27599, United States.
authors.forename: Zhenfa
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Environmental Sciences and Engineering, University of North Carolina , Chapel Hill, North Carolina 27599, United States.
authors.forename: Avram
authors.initials: A
authors.lastname: Gold
authors.affiliation: Department of Environmental Sciences and Engineering, University of North Carolina , Chapel Hill, North Carolina 27599, United States.
authors.forename: Jason D
authors.initials: JD
authors.lastname: Surratt
authors.affiliation: Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory Richland, Washington 99352, United States.
authors.forename: John E
authors.initials: JE
authors.lastname: Shilling
authors.forename: Joel A
authors.initials: JA
authors.lastname: Thornton
mesh_terms: D000336:Aerosols; D000393:Air Pollutants; D001272:Atmosphere / Q000737:chemistry*; D009569:Nitric Oxide / Q000737:chemistry; D009589:Nitrogen Oxides; D010084:Oxidation-Reduction
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D009589:Nitrogen Oxides; D009569:Nitric Oxide