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Title: Controlled nitric oxide production via O( 1D)+N 2O reactions for use in oxidation flow reactor studies

Oxidation flow reactors that use low-pressure mercury lamps to produce hydroxyl (OH) radicals are an emerging technique for studying the oxidative aging of organic aerosols. Here, ozone (O 3) is photolyzed at 254 nm to produce O( 1D) radicals, which react with water vapor to produce OH. However, the need to use parts-per-million levels of O 3 hinders the ability of oxidation flow reactors to simulate NO x-dependent secondary organic aerosol (SOA) formation pathways. Simple addition of nitric oxide (NO) results in fast conversion of NO x (NO+NO 2) to nitric acid (HNO 3), making it impossible to sustain NO x at levels that are sufficient to compete with hydroperoxy (HO 2) radicals as a sink for organic peroxy (RO 2) radicals. We developed a new method that is well suited to the characterization of NO x-dependent SOA formation pathways in oxidation flow reactors. NO and NO 2 are produced via the reaction O( 1D) + N 2O → 2NO, followed by the reaction NO + O 3 → NO 2+O 2. Laboratory measurements coupled with photochemical model simulations suggest that O( 1D) + N 2O reactions can be used to systematically vary the relative branching ratio of RO 2more » + NO reactions relative to RO 2 + HO 2 and/or RO 2 + RO 2 reactions over a range of conditions relevant to atmospheric SOA formation. We demonstrate proof of concept using high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) measurements with nitrate (NO 3 -) reagent ion to detect gas-phase oxidation products of isoprene and α-pinene previously observed in NO x-influenced environments and in laboratory chamber experiments.« less
Authors:
 [1] ;  [2] ; ORCiD logo [2] ;  [2] ; ORCiD logo [2] ;  [2] ; ORCiD logo [3] ;  [4] ; ORCiD logo [1] ;  [2] ; ORCiD logo [2] ;  [5] ;  [6] ;  [7]
  1. Aerodyne Research, Inc., Billerica, MA (United States); Boston College, Chestnut Hill, MA (United States). Dept. of Chemistry
  2. Aerodyne Research, Inc., Billerica, MA (United States)
  3. Univ. of Helsinki (Finland). Dept. of Physics
  4. Nanjing Univ. (China). Joint International Research Lab. of Atmospheric and Earth System Sciences, School of Atmospheric Sciences; Univ. of Helsinki (Finland). Dept. of Physics
  5. Boston College, Chestnut Hill, MA (United States). Dept. of Chemistry
  6. Aerodyne Research, Inc., Billerica, MA (United States); Univ. of Helsinki (Finland). Dept. of Physics
  7. Pennsylvania State Univ., University Park, PA (United States)
Publication Date:
Grant/Contract Number:
SC0006980; SC0011935; AGS-1536939; AGS-1537446; AGS-1537009
Type:
Accepted Manuscript
Journal Name:
Atmospheric Measurement Techniques (Online)
Additional Journal Information:
Journal Name: Atmospheric Measurement Techniques (Online); Journal Volume: 10; Journal Issue: 6; Journal ID: ISSN 1867-8548
Publisher:
European Geosciences Union
Research Org:
Boston College, Chestnut Hill, MA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1425615