title: Effect of Organic Coatings, Humidity and Aerosol Acidity on Multiphase Chemistry of Isoprene Epoxydiols.
abstract: Multiphase chemistry of isomeric isoprene epoxydiols (IEPOX) has been shown to be the dominant source of isoprene-derived secondary organic aerosol (SOA). Recent studies have reported particles composed of ammonium bisulfate (ABS) mixed with model organics exhibit slower rates of IEPOX uptake. In the present study, we investigate the effect of atmospherically relevant organic coatings of α-pinene (AP) SOA on the reactive uptake of trans-β-IEPOX onto ABS particles under different conditions and coating thicknesses. Single particle mass spectrometry was used to characterize in real-time particle size, shape, density, and quantitative composition before and after reaction with IEPOX. We find that IEPOX uptake by pure sulfate particles is a volume-controlled process, which results in particles with uniform concentration of IEPOX-derived SOA across a wide range of sizes. Aerosol acidity was shown to enhance IEPOX-derived SOA formation, consistent with recent studies. The presence of water has a weaker impact on IEPOX-derived SOA yield, but significantly enhanced formation of 2-methyltetrols, consistent with offline filter analysis. In contrast, IEPOX uptake by ABS particles coated with AP-derived SOA is lower compared to that of pure ABS particles, strongly dependent on particle composition, and therefore on particle size.
authors.affiliation: Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-7400, United States.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Riva
authors.affiliation: Pacific Northwest National Laboratory , 3335 Innovation Boulevard, Richland, Washington 99354, United States.
authors.forename: David M
authors.initials: DM
authors.lastname: Bell
authors.affiliation: Department of Chemistry, Aarhus University , Langelandsgade 140, DK-8000 Aarhus, Denmark.
authors.forename: Anne-Maria Kaldal
authors.initials: AM
authors.lastname: Hansen
authors.affiliation: Department of Environmental Science, Policy, and Management, University of California , Berkeley, California 94720, United States.
authors.forename: Greg T
authors.initials: GT
authors.lastname: Drozd
authors.affiliation: Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-7400, United States.
authors.forename: Zhenfa
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-7400, United States.
authors.forename: Avram
authors.initials: A
authors.lastname: Gold
authors.affiliation: Imre Consulting , Richland, Washington 99352, United States.
authors.forename: Dan
authors.initials: D
authors.lastname: Imre
authors.affiliation: Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-7400, United States.
authors.forename: Jason D
authors.initials: JD
authors.lastname: Surratt
authors.affiliation: Department of Chemistry, Aarhus University , Langelandsgade 140, DK-8000 Aarhus, Denmark.
authors.forename: Marianne
authors.initials: M
authors.lastname: Glasius
authors.affiliation: Pacific Northwest National Laboratory , 3335 Innovation Boulevard, Richland, Washington 99354, United States.
authors.forename: Alla
authors.initials: A
authors.lastname: Zelenyuk
mesh_terms: D000143:Acids / Q000737:chemistry; D000336:Aerosols; D001272:Atmosphere / Q000737:chemistry*; D004852:Epoxy Compounds / Q000737:chemistry; D006813:Humidity
chemical_list: D000143:Acids; D000336:Aerosols; D004852:Epoxy Compounds