Gas-Particle Partitioning and SOA Yields of Organonitrate Products from NO3‑Initiated Oxidation of Isoprene under Varied Chemical Regimes

• Published in: ACS earth and space chemistry Vol. 5; no. 4; pp. 785 - 800
• Main Authors: Brownwood, Bellamy, Turdziladze, Avtandil, Hohaus, Thorsten, Wu, Rongrong, Mentel, Thomas F, Carlsson, Philip T. M, Tsiligiannis, Epameinondas, Hallquist, Mattias, Andres, Stefanie, Hantschke, Luisa, Reimer, David, Rohrer, Franz, Tillmann, Ralf, Winter, Benjamin, Liebmann, Jonathan, Brown, Steven S, Kiendler-Scharr, Astrid, Novelli, Anna, Fuchs, Hendrik, Fry, Juliane L
• Format: Journal Article
• Language: English
• Published: American Chemical Society 15.04.2021
• Subjects: Analytical Chemistry; Analytisk kemi; Chemical Sciences; chemistry; Climate Research; Earth and Related Environmental Sciences; Fysikalisk kemi; gas-aerosol; Geochemistry & Geophysics; Geovetenskap och miljövetenskap; isoprene; Kemi; Klimatforskning; Meteorologi och atmosfärforskning; Meteorology and Atmospheric Sciences; n2o5; nitrate; nitrate radical oxidation; no3; Organic Chemistry; Organisk kemi; oxidation mechanism; partitioning; peroxy radicals; Physical Chemistry; ring-down; secondary organic aerosol; spectrometer; secondary organic aerosol; oxidation mechanism; gas-aerosol partitioning; nitrate; isoprene; peroxy radicals
• ISSN: 2472-3452; 2472-3452
• DOI: 10.1021/acsearthspacechem.0c00311

Alkyl nitrate (AN) and secondary organic aerosol (SOA) from the reaction of nitrate radicals (NO3) with isoprene were observed in the Simulation of Atmospheric PHotochemistry In a large Reaction (SAPHIR) chamber during the NO3Isop campaign in August 2018. Based on 15 day-long experiments under various reaction conditions, we conclude that the reaction has a nominally unity molar AN yield (observed range 90 ± 40%) and an SOA mass yield of OA + organic nitrate aerosol of 13–15% (with ∼50 μg m–3 inorganic seed aerosol and 2–5 μg m–3 total organic aerosol). Isoprene (5–25 ppb) and oxidant (typically ∼100 ppb O3 and 5–25 ppb NO2) concentrations and aerosol composition (inorganic and organic coating) were varied while remaining close to ambient conditions, producing similar AN and SOA yields under all regimes. We observe the formation of dinitrates upon oxidation of the second double bond only once the isoprene precursor is fully consumed. We determine the bulk partitioning coefficient for ANs (K p ∼ 10–3 m3 μg–1), indicating an average volatility corresponding to a C5 hydroxy hydroperoxy nitrate.