Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published January 19, 2022 | Published + Supplemental Material
Journal Article Open

Secondary organic aerosol formation from the oxidation of decamethylcyclopentasiloxane at atmospherically relevant OH concentrations


Decamethylcyclopentasiloxane (D5, C₁₀H₃₀O₅Si₅) is measured at parts per trillion (ppt) levels outdoors and parts per billion (ppb) levels indoors. Primarily used in personal care products, its outdoor concentration is correlated to population density. Since understanding the aerosol formation potential of volatile chemical products is critical to understanding particulate matter in urban areas, the secondary organic aerosol yield of D5 was studied under a wide range of OH concentrations and, correspondingly, OH exposures using both batch-mode chamber and continuously run flow tube experiments. These results were comprehensively analyzed and compared to two other secondary organic aerosol (SOA) yield datasets from literature. It was found that the SOA yield from the oxidation of D5 is extremely dependent on either the OH concentration or exposure. For OH concentrations of ≲ 10⁷ molec. cm⁻³ or OH exposures of ≲ 2 × 10¹¹, molec. s cm⁻³ the SOA yield is largely < 5 % and usually ∼ 1 %. This is significantly lower than SOA yields previously reported. Using a two-product absorptive partitioning model for the upper bound SOA yields, the stoichiometric mass fraction and absorptive partitioning coefficients are, for the first product, α₁ = 0.056 and K_(OM,1) = 0.022 m³ µg⁻¹; for the second product, they are α₂ = 7.7 and K_(OM,2) = 4.3 × 10⁻⁵ m³ µg⁻¹. Generally, there are high SOA yields (> 90 %) at OH mixing ratios of 5 × 10⁹  molec. cm⁻³ or OH exposures above 10¹² molec. s cm⁻³.

Additional Information

© Author(s) 2022. This work is distributed under the Creative Commons Attribution 4.0 License. Received: 28 Apr 2021 – Discussion started: 03 May 2021 – Revised: 14 Dec 2021 – Accepted: 15 Dec 2021 – Published: 19 Jan 2022. The authors would like to thank Nathan Dalleska for his assistance with the GC-FID, John Crounse for his general help and for synthesis of CF₃O⁻ for the CIMS, Paul Wennberg for the use of his FT-IR and for his insight during discussions of the system, Lu Xu and Benjamin Schulze for useful input, and Mitchell Alton and Eleanor Browne for helpful discussions. This research has been supported by the California Air Resources Board (grant no. 18RD009) and the National Science Foundation (grant no. 1745301). Author contributions. SMC designed the experiments, carried out the data collection and analysis, and wrote the manuscript. YH assisted with the CPOT experiments. RSB participated in discussions about the study. QL measured the aerosol density. DRC III secured funding for the project. JHS supervised the work. All authors reviewed and edited the manuscript. Data availability. Chamber data are available upon request and through the Index of Chamber Atmospheric Research in the United States (ICARUS), experiment sets 220 and 221: https://icarus.ucdavis.edu/experimentset/220 (Charan, 2021) and https://icarus.ucdavis.edu/experimentset/221 (Charan and Huang, 2021). The supplement related to this article is available online at: https://doi.org/10.5194/acp-22-917-2022-supplement. he contact author has declared that neither they nor their co-authors have any competing interests. Review statement. This paper was edited by Frank Keutsch and reviewed by three anonymous referees.

Attached Files

Published - acp-22-917-2022.pdf

Supplemental Material - acp-22-917-2022-supplement.pdf


Files (3.4 MB)
Name Size Download all
1.0 MB Preview Download
2.4 MB Preview Download

Additional details

September 15, 2023
October 23, 2023