Title: | "Gas-Phase Chlorine Radical Oxidation of Alkanes: Effects of Structural Branching, NO(x), and Relative Humidity Observed during Environmental Chamber Experiments" |
Author(s): | Jahn LG; Wang DS; Dhulipala SV; Ruiz LH; |
Address: | "McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, 78712 Texas, United States. Now at Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland. Now at Department of Mechanical Engineering, The University of British Columbia, V6T 1Z4 Vancouver, Canada" |
ISSN/ISBN: | 1520-5215 (Electronic) 1089-5639 (Linking) |
Abstract: | "Chlorine-initiated oxidation of alkanes has been shown to rapidly form secondary organic aerosol (SOA) at higher yields than OH-alkane reactions. However, the effects of alkane volatile organic compound precursor structure and the reasons for the differences in SOA yield from OH-alkane reactions remain unclear. In this work, we investigated the effects of alkane molecular structure on oxidation by chlorine radical (Cl) and resulting formation of SOA through a series of laboratory chamber experiments, utilizing data from an iodide chemical ionization mass spectrometer and an aerosol chemical speciation monitor. Experiments were conducted with linear, branched, and branched cyclic C(10) alkane precursors under different NO(x) and RH conditions. Observed product fragmentation patterns during the oxidation of branched alkanes demonstrate the abstraction of primary hydrogens by Cl, confirming a key difference between OH- and Cl-initiated oxidation of alkanes and providing a possible explanation for higher SOA production from Cl-initiated oxidation. Low-NO(x) conditions led to higher SOA production. SOA formed from butylcyclohexane under low NO(x) conditions contained higher fractions of organic acids and lower volatility molecules that were less prone to oligomerization relative to decane SOA. Branched alkanes produced less SOA, and branched cycloalkanes produced more SOA than linear n-alkanes, consistent with past work on OH-initiated reactions. Overall, our work provides insights into the differences between Cl- and OH-initiated oxidation of alkanes of different structures and the potential significance of Cl as an atmospheric oxidant" |
Notes: | "PubMed-not-MEDLINEJahn, Leif G Wang, Dongyu S Dhulipala, Surya Venkatesh Ruiz, Lea Hildebrandt eng 2021/08/13 J Phys Chem A. 2021 Aug 26; 125(33):7303-7317. doi: 10.1021/acs.jpca.1c03516. Epub 2021 Aug 12" |