A. J. Kwan

TL;DR: In this article, the role of epoxydiols of isoprene and methacryloylperoxynitrate (MPAN) in the formation of secondary organic aerosol (SOA) was identified.

Abstract: Secondary organic aerosol (SOA) formation from the photooxidation of one monoterpene (α-pinene) and two sesquiterpenes (longifolene and aromadendrene) is investigated in the Caltech environmental chambers. The effect of NOx on SOA formation for these biogenic hydrocarbons is evaluated by performing photooxidation experiments under varying NOx conditions. The NOx dependence of α-pinene SOA formation follows the same trend as that observed previously for a number of SOA precursors, including isoprene, in which SOA yield (defined as the ratio of the mass of organic aerosol formed to the mass of parent hydrocarbon reacted) decreases as NOx level increases. The NOx dependence of SOA yield for the sesquiterpenes, longifolene and aromadendrene, however, differs from that determined for isoprene and α-pinene; the aerosol yield under high-NOx conditions substantially exceeds that under low-NOx conditions. The reversal of the NOx dependence of SOA formation for the sesquiterpenes is consistent with formation of relatively low-volatility organic nitrates, and/or the isomerization of large alkoxy radicals leading to less volatile products. Analysis of the aerosol chemical composition for longifolene confirms the presence of organic nitrates under high-NOx conditions. Consequently the formation of SOA from certain biogenic hydrocarbons such as sesquiterpenes (and possibly large anthropogenic hydrocarbons as well) may be more efficient in polluted air.

TL;DR: In this article, the authors investigated secondary organic aerosol (SOA) formation from the reaction of isoprene with nitrate radicals (NO 3 ) in the Caltech indoor chambers.

TL;DR: These measurements provide unique observational constraints on the chemistry occurring downwind of convection and the rate at which air in the UT is recycled, which provide quantitative measures that can be used to evaluate global climate and chemistry models.

TL;DR: In this paper, peroxy radical reactions from the NO3-initiated oxidation of isoprene are studied with both gas chromatography and a chemical ionization mass spectrometry technique.