title: Effect of acidity on secondary organic aerosol formation from isoprene.
abstract: The effect of particle-phase acidity on secondary organic aerosol (SOA) formation from isoprene is investigated in a laboratory chamber study, in which the acidity of the inorganic seed aerosol was controlled systematically. The observed enhancement in SOA mass concentration is closely correlated to increasing aerosol acidity (R2 = 0.979). Direct chemical evidence for acid-catalyzed particle-phase reactions was obtained from the SOA chemical analyses. Aerosol mass concentrations for the 2-methyltetrols, as well as the newly identified sulfate esters, both of which serve as tracers for isoprene SOA in ambient aerosols, increased significantly with enhanced aerosol acidity. Aerosol acidities, as measured in nmol of H+ m(-3), employed in the present study are in the same range as those observed in tropospheric aerosol collected from the eastern U.S.
authors.affiliation: Department of Chemistry and Departments of Chemical Engineering and Environmental Science and Engineering, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Jason D
authors.initials: JD
authors.lastname: Surratt
authors.forename: Michael
authors.initials: M
authors.lastname: Lewandowski
authors.forename: John H
authors.initials: JH
authors.lastname: Offenberg
authors.forename: Mohammed
authors.initials: M
authors.lastname: Jaoui
authors.forename: Tadeusz E
authors.initials: TE
authors.lastname: Kleindienst
authors.forename: Edward O
authors.initials: EO
authors.lastname: Edney
authors.forename: John H
authors.initials: JH
authors.lastname: Seinfeld
mesh_terms: D000336:Aerosols / Q000737:chemistry*; D002070:Butadienes / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry; D005740:Gases / Q000737:chemistry; D045782:Hemiterpenes / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D009569:Nitric Oxide / Q000737:chemistry; D009930:Organic Chemicals / Q000737:chemistry*; D010084:Oxidation-Reduction; D010420:Pentanes / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization