| Title: | Heterogeneous Ozonolysis of Squalene: Gas-Phase Products Depend on Water Vapor Concentration |
| Author(s): | Arata C; Heine N; Wang N; Misztal PK; Wargocki P; Beko G; Williams J; Nazaroff WW; Wilson KR; Goldstein AH; |
| Address: | "Chemical Sciences Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States. Air Chemistry Department , Max Planck Institute for Chemistry , 55128 Mainz , Germany. Department of Civil Engineering , Technical University of Denmark , 2800 Kgs. Lyngby , Denmark" |
| ISSN/ISBN: | 1520-5851 (Electronic) 0013-936X (Linking) |
| Abstract: | "Previous work examining the condensed-phase products of squalene particle ozonolysis found that an increase in water vapor concentration led to lower concentrations of secondary ozonides, increased concentrations of carbonyls, and smaller particle diameter, suggesting that water changes the fate of the Criegee intermediate. To determine if this volume loss corresponds to an increase in gas-phase products, we measured gas-phase volatile organic compound (VOC) concentrations via proton-transfer-reaction time-of-flight mass spectrometry. Studies were conducted in a flow-tube reactor at atmospherically relevant ozone (O(3)) exposure levels (5-30 ppb h) with pure squalene particles. An increase in water vapor concentration led to strong enhancement of gas-phase oxidation products at all tested O(3) exposures. An increase in water vapor from near zero to 70% relative humidity (RH) at high O(3) exposure increased the total mass concentration of gas-phase VOCs by a factor of 3. The observed fraction of carbon in the gas-phase correlates with the fraction of particle volume lost. Experiments involving O(3) oxidation of shirts soiled with skin oil confirms that the RH dependence of gas-phase reaction product generation occurs similarly on surfaces containing skin oil under realistic conditions. Similar behavior is expected for O(3) reactions with other surface-bound organics containing unsaturated carbon bonds" |
| Keywords: | Mass Spectrometry Organic Chemicals *Ozone *Squalene Steam; |
| Notes: | "MedlineArata, Caleb Heine, Nadja Wang, Nijing Misztal, Pawel K Wargocki, Pawel Beko, Gabriel Williams, Jonathan Nazaroff, William W Wilson, Kevin R Goldstein, Allen H eng Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. 2019/11/24 Environ Sci Technol. 2019 Dec 17; 53(24):14441-14448. doi: 10.1021/acs.est.9b05957. Epub 2019 Dec 6" |
