Polyolefinic monoterpenes represent a potentially important but understudied source of organic nitrates (ON) and secondary organic aerosol (SOA) following oxidation due to their high reactivity and propensity for multi-stage chemistry. Recent modeling work suggests that the oxidation of polyolefinic γ-terpinene can be the dominant source of nighttime ON in a mixed forest environment. However, the ON yields, aerosol partitioning behavior, and SOA yields from γ-terpinene oxidation by the nitrate radical (NO₃), an important nighttime oxidant, have not been determined experimentally. In this work, we present a comprehensive experimental investigation of the total (gas + particle) ON, hydroxy nitrate, and SOA yields following γ-terpinene oxidation by NO₃. Under dry conditions, the hydroxy nitrate yield = 4(+1/−3) %, total ON yield = 14(+3/−2) %, and SOA yield ≤10% under atmospherically-relevant particle mass loadings, similar to those for α-pinene + NO₃. Using a chemical box model, we show that the measured concentrations of NO₂ and γ-terpinene hydroxy nitrates can be reliably simulated from α-pinene + NO₃ chemistry. This suggests that NO₃ addition to either of the two internal double bonds of γ-terpinene primarily decomposes forming a relatively volatile keto–aldehyde, reconciling the small SOA yield observed here and for other internal olefinic terpenes. Based on aerosol partitioning analysis and identification of speciated particle-phase ON applying high-resolution liquid chromatography–mass spectrometry, we estimate that a significant fraction of the particle-phase ON has the hydroxy nitrate moiety. This work greatly contributes to our understanding of ON and SOA formation from polyolefin monoterpene oxidation, which could be important in the northern continental U.S. and Midwest, where polyolefinic monoterpene emissions are greatest.

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For the full article please visit http://www.atmos-chem-phys-discuss.net/acp-2017-249/

Researchers should cite this work as follows:

• Slade, J. H. (2017). Dataset for Nitrate radical oxidation of γ-terpinene: hydroxy nitrate, total organic nitrate, and secondary organic aerosol yields. Purdue University Research Repository. doi:10.4231/R7CZ35BD

  BibTex | EndNote

1. Chemistry
2. EAPS (Dept)
3. Earth and Atmospheric Sciences
4. Monoterpenes
5. Nitrate Radical
6. Organic Nitrates
7. Secondary Organic Aerosol