@article {34544,
	title = {Phase Behavior of Internal Mixtures of Hydrocarbon-like Primary Organic Aerosol and Secondary Aerosol Based on Their Differences in Oxygen-to-Carbon Ratios},
	journal = {ENVIRONMENTAL SCIENCE \& TECHNOLOGY},
	volume = {56},
	year = {2022},
	month = {MAR 2022},
	pages = {3960-3973},
	abstract = {<p>The phase behavior, the number and type of phases, in atmospheric particles containing mixtures of hydrocarbon-like organic aerosol (HOA) and secondary organic aerosol (SOA) is important for predicting their impacts on air pollution, human health, and climate. Using a solvatochromic dye and fluorescence microscopy, we determined the phase behavior of 11 HOA proxies (O/C = 0\&ndash;0.29) each mixed with 7 different SOA materials generated in environmental chambers (O/C 0.4\&ndash;1.08), where O/C represents the average oxygen-to-carbon atomic ratio. Out of the 77 different HOA + SOA mixtures studied, we observed two phases in 88\% of the cases. The phase behavior was independent of relative humidity over the range between 90\% and \&lt;5\%. A clear trend was observed between the number of phases and the difference between the average O/C ratios of the HOA and SOA components (ΔO/C). Using a threshold ΔO/C of 0.265, we were able to predict the phase behavior of 92\% of the HOA + SOA mixtures studied here, with one-phase particles predicted for ΔO/C \&lt; 0.265 and two-phase particles predicted for ΔO/C \&ge; 0.265. The threshold ΔO/C value provides a relatively simple and computationally inexpensive framework for predicting the number of phases in internal SOA and HOA mixtures in atmospheric models.</p>},
	doi = {10.1021/acs.est.1c07691},
	url = {https://pubs.acs.org/doi/10.1021/acs.est.1c07691},
	author = {Mahrt, F. and Huang, Y. and Zaks, J. and Devi, A. and Peng, L. and Ohno, P. E. and Qin, Y. M. and Martin, S.T. and Ammann, M. and Bertram, A. K.}
}
