Accretion Product Formation from Ozonolysis and OH Radical Reaction of α-Pinene: Mechanistic Insight and the Influence of Isoprene and Ethylene

• DOI: 10.1021/acs.est.8b02210
• Publication Date: 2018-09-07T20:04:50Z
• Authors: Torsten Berndt; Bernhard Mentler; Wiebke Scholz; Lukas Fischer; Hartmut Herrmann; Markku Kulmala; Armin Hansel
• Keywords: Isoprene; Pinene

α-Pinene (C10H16) represents one of the most important biogenic emissions in atmosphere. Its oxidation products can significantly contribute to secondary organic aerosol (SOA) formation. Here, we report on formation mechanism C19 and C20 accretion from α-pinene oxidation, which are believed be efficient SOA precursors. Measurements have been performed a free-jet flow system. Detection RO2 radicals was carried out by recent mass spectrometric techniques using different ionization schemes. Observed C10-RO2 ozonolysis were O,O-C10H15(O2) xO2 with x = 0, 1, 2, 3 OH radical reaction HO-C10H16(O2)αO2 α 2. All detected explained via + R'O2 → ROOR' O2 starting measured radicals. We speculate that formed an analogous way assuming CH2O elimination. Addition isoprene (C5H8), producing C5-RO2 radicals, leads C15 cross-reactions This process is competing C19/C20 pure oxidation. A similar behavior has observed for ethylene additives form C12 products. In atmosphere, complex product spectrum self- available expected. Modeling atmospheric conditions revealed only reduced factor 1.2 or 3.6 isoprene-dominated environments 2- 15-fold concentration over α-pinene, respectively, as present forested areas.