Molecular composition and volatility of isoprene photochemical oxidation secondary organic aerosol under low- and high-NO x conditions
Here, we present measurements of secondary organic aerosol (SOA) formation from isoprene photochemical oxidation in an environmental simulation chamber at a variety of oxidant conditions and using dry neutral seed particles to suppress acid-catalyzed multiphase chemistry. A high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) utilizing iodide-adduct ionization coupled to the Filter Inlet for Gases and Aerosols (FIGAERO) allowed for simultaneous online sampling of the gas and particle composition. Under high-HO 2 and low-NO conditions, highly oxygenated (O : C ≥ 1) C 5 compounds were major components (~50%) of SOA. The SOA composition and effective volatility evolved both as a function of time and as a function of input NO concentrations. Organic nitrates increased in both the gas and particle phases as input NO increased, but the dominant non-nitrate particle-phase components monotonically decreased. We use comparisons of measured and predicted gas-particle partitioning of individual components to assess the validity of literature-based group-contribution methods for estimating saturation vapor concentrations. While there is evidence for equilibrium partitioning being achieved on the chamber residence timescale (5.2 h) for some individual components, significant errors in group-contribution methods are revealed. In addition, >30% of the SOA mass, detected as low-molecular-weight semivolatile compounds, cannot be reconciled withmore »
- Authors:
-
[1] ; [1];
[2] ; [2]; [3]; [4]; [1];
[2] ;
[5] ; [6]; [7]; [7]; [7]; [8]; [8]; [1]
- Univ. of Washington, Seattle, WA (United States)
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Univ. of Washington, Seattle, WA (United States); Univ. of Miami, Coral Gables, FL (United States)
- Univ. of Washington, Seattle, WA (United States); Paul Scherrer Inst. (PSI), Zurich (Switzerland)
- Univ. of Washington, Seattle, WA (United States); Karlsruhe Institute of Technology, Karlsruhe (Germany)
- Univ. of Gothenburg, Gothenburg (Sweden)
- Univ. of North Carolina, Chapel Hill, NC (United States)
- Harvard Univ., Cambridge, MA (United States)
- Publication Date:
- Report Number(s):
- PNNL-SA-119934
Journal ID: ISSN 1680-7324; KP1701000
- Grant/Contract Number:
- AC05-76RL01830; SC0011791
- Type:
- Published Article
- Journal Name:
- Atmospheric Chemistry and Physics (Online)
- Additional Journal Information:
- Journal Name: Atmospheric Chemistry and Physics (Online); Journal Volume: 17; Journal Issue: 1; Journal ID: ISSN 1680-7324
- Publisher:
- European Geosciences Union
- Research Org:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Org:
- USDOE Office of Science (SC)
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 54 ENVIRONMENTAL SCIENCES; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; isoprene; photochemical oxidation; secondary organic aerosol
- OSTI Identifier:
- 1338140
- Alternate Identifier(s):
- OSTI ID: 1339791; OSTI ID: 1390603