Learn More
A series of outdoor chamber experiments has been used to establish and characterize the significant atmospheric aerosol-forming potentials of the most prevalent biogenic hydrocarbons emitted by vegetation. These compounds were also studied to elucidate the effect of structure on aerosol yield for these types of compounds. Because oxidation products(More)
[1] The Aerodyne Aerosol Mass Spectrometer (AMS) has been designed to measure size-resolved mass distributions and total mass loadings of volatile and semivolatile chemical species in/on submicron particles. This paper describes the application of this instrument to ambient aerosol sampling. The AMS uses an aerodynamic lens to focus the particles into a(More)
Secondary organic aerosol (SOA) formation from the photooxidation of m-xylene, toluene, and benzene is investigated in the Caltech environmental chambers. Experiments are performed under two limiting NO x conditions; under high-NO x conditions the peroxy radicals (RO 2) react only with NO, while under low-NO x conditions they react only with HO 2. For all(More)
Biogenic hydrocarbons emitted by vegetation are important contributors to secondary organic aerosol (SOA), but the aerosol formation mechanisms are incompletely understood. In this study, the formation of aerosols and gas-phase products from the ozonolysis and photooxidation of a series of biogenic hydrocarbons (isoprene, 8 monoterpenes, 4 sesquiterpenes,(More)
A series of experiments has been conducted in the Caltech indoor smog chamber facility to investigate the water uptake properties of aerosol formed by oxidation of various organic precursors. Secondary organic aerosol (SOA) from simple and substituted cycloalkenes (C 5-C 8) is produced in dark ozonolysis experiments in a dry chamber (RH∼5%). Biogenic SOA(More)
[1] The oxidation of isoprene (2-methyl-1,3-butadiene) is known to play a central role in the photochemistry of the troposphere, but is generally not considered to lead to the formation of secondary organic aerosol (SOA), due to the relatively high volatility of known reaction products. However, in the chamber studies described here, we measure SOA(More)
Isoprene is a significant source of atmospheric organic aerosol; however, the oxidation pathways that lead to secondary organic aerosol (SOA) have remained elusive. Here, we identify the role of two key reactive intermediates, epoxydiols of isoprene (IEPOX = beta-IEPOX + delta-IEPOX) and methacryloylperoxynitrate (MPAN), which are formed during isoprene(More)
The elemental composition of laboratory chamber secondary organic aerosol (SOA) from glyoxal uptake, α-pinene ozonolysis, isoprene photooxidation, single-ring aromatic photooxidation, and naphthalene photooxidation is evaluated using Aerodyne high-resolution time-of-flight mass spectrometer data. SOA O/C ratios range from 1.13 for glyoxal uptake experiments(More)
A series of sunlight-irradiated, smog-chamber experiments confirmed that the atmospheric organic aerosol formation potential of whole gasoline vapor cna be accounted for solely in terms of the aromatic fraction of the fuel. The total amount of secondary organic aerosol produced from the atmospheric oxidation of whole gasoline vapor can be represented as the(More)