| Title: | Peroxy Radical Autoxidation and Sequential Oxidation in Organic Nitrate Formation during Limonene Nighttime Oxidation |
| Author(s): | Mayorga R; Xia Y; Zhao Z; Long B; Zhang H; |
| Address: | "Department of Chemistry, University of California, Riverside, California 92507, United States. School of Materials Science and Engineering, Guizhou Minzu University, Guiyang 550025, China" |
| ISSN/ISBN: | 1520-5851 (Electronic) 0013-936X (Linking) |
| Abstract: | "Limonene is an abundant monoterpene released into the atmosphere via biogenic emissions and biomass burning. However, the atmospheric oxidation and secondary organic aerosol (SOA) formation mechanisms of limonene, especially during nighttime, remain largely understudied. In this work, limonene was oxidized synergistically by ozone (O(3)) and nitrate radicals (NO(3)) in a flow tube reactor and a continuous flow stirred tank reactor. Upon oxidation, many highly oxidized organic nitrates and nitrooxy peroxy radicals (RO(2)) were observed in the gas phase within 1 min. Combining quantum chemical calculations with kinetic simulations, we found that the primary nitrooxy RO(2) (C(10)H(16)NO(5)) through NO(3) addition at the more substituted endocyclic double bond and at the exocyclic double bond (previously considered as minor pathways) can undergo autoxidation with rate constants of around 0.02 and 20 s(-1) at 298 K, respectively. These pathways could explain a major portion of the observed highly oxidized organic nitrates. In the SOA, highly oxidized mono- and dinitrates (e.g., C(10)H(17)NO(7-8) and C(10)H(16),(18)N(2)O(8-10)) make up a significant contribution, highlighting nitrooxy RO(2) autoxidation and sequential NO(3) oxidation of limonene. The same organic nitrates are also observed in ambient aerosol during biomass burning and nighttime in the southeastern United States. Therefore, the present work provides new insights into the nighttime oxidation of limonene and SOA formation in the atmosphere" |
| Keywords: | Limonene Nitrates/chemistry *Air Pollutants/analysis Aerosols/chemistry *Ozone/chemistry Organic Chemicals Nitrogen Oxides biogenic volatile organic compounds dinitrate highly oxidized molecules nitrate radical secondary organic aerosol; |
| Notes: | "MedlineMayorga, Raphael Xia, Yu Zhao, Zixu Long, Bo Zhang, Haofei eng Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. 2022/10/26 Environ Sci Technol. 2022 Nov 15; 56(22):15337-15346. doi: 10.1021/acs.est.2c04030. Epub 2022 Oct 25" |
