The relationship between the oxidation state and relative volatility of secondary organic aerosol (SOA) from the oxidation of a wide range of hydrocarbons is investigated using a fast-stepping, scanning thermodenuder interfaced with a high resolution time-of-flight aerosol mass spectrometer (AMS). SOA oxidation state varied widely across the investigated range of parent hydrocarbons but was relatively stable for replicate experiments using a single hydrocarbon precursor. On average, unit mass resolution indicators of SOA oxidation (e.g., AMS f43 and f44) are consistent with previously reported values. Linear regression of H:C vs O:C obtained from parameterization of f43 and f44 and elemental analysis of high resolution spectra in Van Krevelen space both yield a slope of ~0.5 across different SOA types. A similar slope was obtained for a distinct subset of toluene/NOx reactions in which the integrated oxidant exposure was varied to alter oxidation. The relative volatility of different SOA types displays similar variability and is strongly correlated with SOA oxidation state (OSC). On average, relatively low oxidation and volatility were observed for aliphatic alkene (including terpenes) and n-alkane SOA while the opposite is true for mono- and polycyclic aromatic hydrocarbon SOA. Effective enthalpy for total chamber aerosol obtained from volatility differential mobility analysis is also highly correlated with OSC indicating a primary role for oxidation levels in determining the volatility of chamber SOA. Effective enthalpies for chamber SOA are substantially lower than those of neat organic standards but are on the order of those obtained for partially oligomerized glyoxal and methyl glyoxal. This dataset is associated with the following publication: Docherty, K., E. Corse, M. Jaoui, J. Offenberg, T. Kleindienst, J. Krug, T. Riedel, and M. Lewandowski. Trends in the oxidation and relative volatility of chamber-generated secondary organic aerosol. AEROSOL SCIENCE AND TECHNOLOGY. Taylor & Francis, Inc., Philadelphia, PA, USA, 52(9): 992-1004, (2018).

Tracers of secondary organic aerosols (SOA) from thirteen aromatic hydrocarbons were quantified in laboratory smog chamber experiments. Class-specific SOA tracers emerged, including 2,3-dihydroxy-4-oxo-pentatonic acid (DHOPA) from monoaromatic volatile organic compounds (VOCs), phthalic acid from naphthalene and 1-methylnaphthalene, and methyl-nitrocatechol isomers from o,m,p-cresol oxidation. Organic carbon mass fractions (fSOC) for these and other tracers were determined and extend the SOA tracer method widely used to apportion biogenic SOC. The extended SOA tracer model was applied to evaluate the sources of SOC in Atlanta, GA during summer 2015 and winter 2016 after modifying the chamber-derived fSOC¬ values to reflect SOA yields and local VOC levels (fSOC’). Monoaromatic, diaromatic, and cresol SOC contributed an average of 24%, 8%, and 0.12% of organic carbon (OC) mass during summer and 17%, 5%, and 0.27% during winter, respectively. Cresol SOC peaked during winter and was highly correlated with levoglucosan (r=0.93, p<0.001), consistent with it originating from biomass burning. Together, aromatic, biogenic, and biomass burning derived SOC accounted for an average of 77% and 28% of OC in summer and winter, respectively. The new understanding of SOA composition from aromatic VOCs advances the tracer-based method by including important precursors of SOC and enables a better understanding of the sources of atmospheric aerosol. This dataset is associated with the following publication: Al-Naiema, I.M., J. Offenberg, C.J. Madler, M. Lewandowski, J. Kettler, T. Fang, and E.A. Stone. Secondary Organic Aerosols from Aromatic Hydrocarbons and their Contribution to Fine Particulate Matter in Atlanta, Georgia. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, USA, 223: 117227, (2020).

Tracers of secondary organic aerosols (SOA) from thirteen aromatic hydrocarbons were quantified in laboratory smog chamber experiments. Class-specific SOA tracers emerged, including 2,3-dihydroxy-4-oxo-pentatonic acid (DHOPA) from monoaromatic volatile organic compounds (VOCs), phthalic acid from naphthalene and 1-methylnaphthalene, and methyl-nitrocatechol isomers from o,m,p-cresol oxidation. Organic carbon mass fractions (fSOC) for these and other tracers were determined and extend the SOA tracer method widely used to apportion biogenic SOC. The extended SOA tracer model was applied to evaluate the sources of SOC in Atlanta, GA during summer 2015 and winter 2016 after modifying the chamber-derived fSOC¬ values to reflect SOA yields and local VOC levels (fSOC’). Monoaromatic, diaromatic, and cresol SOC contributed an average of 24%, 8%, and 0.12% of organic carbon (OC) mass during summer and 17%, 5%, and 0.27% during winter, respectively. Cresol SOC peaked during winter and was highly correlated with levoglucosan (r=0.93, p<0.001), consistent with it originating from biomass burning. Together, aromatic, biogenic, and biomass burning derived SOC accounted for an average of 77% and 28% of OC in summer and winter, respectively. The new understanding of SOA composition from aromatic VOCs advances the tracer-based method by including important precursors of SOC and enables a better understanding of the sources of atmospheric aerosol. This dataset is associated with the following publication: Al-Naiema, I.M., J. Offenberg, C.J. Madler, M. Lewandowski, J. Kettler, T. Fang, and E.A. Stone. Secondary Organic Aerosols from Aromatic Hydrocarbons and their Contribution to Fine Particulate Matter in Atlanta, Georgia. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, USA, 223: 117227, (2020).

Volume concentrations of secondary organic aerosol (SOA) are measured in 139 steady-state, single precursor hydrocarbon oxidation experiments after passing through a temperature controlled inlet. The response to change in temperature is well predicted through a feedforward Artificial Neural Network. The most parsimonious model, as indicated by Akaike’s Information Criterion, Corrected (AIC,C), utilizes 11 input variables, a single hidden layer of 4 tanh activation function nodes, and a single linear output function. This model predicts thermal behavior of single precursor aerosols to less than ± 5%, which is within the measurement uncertainty, while limiting the problem of overfitting. Prediction of thermal behavior of SOA can be achieved by a concise number of descriptors of the precursor hydrocarbon including the number of internal and external double bonds, number of methyl- and ethyl- functional groups, molecular weight, number of ring structures, in addition to the volume of SOA formed, and an indicator of which of four oxidant precursors was used to initiate reactions (NOx photo-oxidation, photolysis of H2O2, ozonolysis, or thermal decomposition of N2O5). Additional input variables, such as, chamber volumetric residence time, relative humidity, initial concentration of oxides of nitrogen, reacted hydrocarbon concentration, and further descriptors of the precursor hydrocarbon, including carbon number, number of oxygen atoms, and number of aromatic ring structures, lead to over fit models, and are unnecessary for an efficient, accurate predictive model of thermal behavior of SOA. This work indicates that predictive statistical modeling methods may be complementary to descriptive techniques for use in parameterization of air quality models. This dataset is associated with the following publication: Offenberg, J., M. Lewandowski, T. Kleindienst, K. Docherty, J. Krug, T. Riedel, D. Olson, and M. Jaoui. Predicting Thermal Behavior of Secondary Organic Aerosols. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, USA, 51(17): 9911-9919, (2017).

Volume concentrations of secondary organic aerosol (SOA) are measured in 139 steady-state, single precursor hydrocarbon oxidation experiments after passing through a temperature controlled inlet. The response to change in temperature is well predicted through a feedforward Artificial Neural Network. The most parsimonious model, as indicated by Akaike’s Information Criterion, Corrected (AIC,C), utilizes 11 input variables, a single hidden layer of 4 tanh activation function nodes, and a single linear output function. This model predicts thermal behavior of single precursor aerosols to less than ± 5%, which is within the measurement uncertainty, while limiting the problem of overfitting. Prediction of thermal behavior of SOA can be achieved by a concise number of descriptors of the precursor hydrocarbon including the number of internal and external double bonds, number of methyl- and ethyl- functional groups, molecular weight, number of ring structures, in addition to the volume of SOA formed, and an indicator of which of four oxidant precursors was used to initiate reactions (NOx photo-oxidation, photolysis of H2O2, ozonolysis, or thermal decomposition of N2O5). Additional input variables, such as, chamber volumetric residence time, relative humidity, initial concentration of oxides of nitrogen, reacted hydrocarbon concentration, and further descriptors of the precursor hydrocarbon, including carbon number, number of oxygen atoms, and number of aromatic ring structures, lead to over fit models, and are unnecessary for an efficient, accurate predictive model of thermal behavior of SOA. This work indicates that predictive statistical modeling methods may be complementary to descriptive techniques for use in parameterization of air quality models. This dataset is associated with the following publication: Offenberg, J., M. Lewandowski, T. Kleindienst, K. Docherty, J. Krug, T. Riedel, D. Olson, and M. Jaoui. Predicting Thermal Behavior of Secondary Organic Aerosols. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, USA, 51(17): 9911-9919, (2017).

Oxidation of the monoterpene Δ3-carene (C10H16) is a potentially important and under-studied source of atmospheric secondary organic aerosol (SOA). We present chamber-based measurements of the speciated gas and particle phases during photochemical oxidation of Δ3-carene. We find evidence of highly oxidized organic molecules (HOM) in the gas phase and relatively low volatility SOA dominated by C7-C10 species. We then use computational methods to develop the first stages of a Δ3-carene photochemical oxidation mechanism and explain some of our measured compositions. We find that alkoxy bond scission of the cyclohexyl ring likely leads to efficient HOM formation, in line with previous studies. We also find a surprising role for the abstraction of primary hydrogens from methyl groups, which has been calculated to be rapid in the α-pinene system, and suggest more research is required to determine if this is more general to other systems and a feature of autoxidation. This work develops a more comprehensive view of Δ3-carene photochemical oxidation products via measurements and lays out a suggested mechanism of oxidation via computationally derived rate coefficients. This dataset is not publicly accessible because: Non-EPA data. It can be accessed through the following means: Please contact Joel Thornton at: thornton@atmos.uw.edu. Format: text files. This dataset is associated with the following publication: D'Ambro, E., N. Hyttinen, K. Møller, S. Iyer, R. Otkjær, D. Bell, J. Liu, F. Lopez-Hilfiker, S. Schobesberger, J. Shilling, A. Zelenyuk, H. Kjaergaard, J. Thornton, and T. Kurten. Pathways to highly oxidized products in the Δ3-Carene + OH system. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, USA, 56(4): 2213-2224, (2022).

Oxidation of the monoterpene Δ3-carene (C10H16) is a potentially important and under-studied source of atmospheric secondary organic aerosol (SOA). We present chamber-based measurements of the speciated gas and particle phases during photochemical oxidation of Δ3-carene. We find evidence of highly oxidized organic molecules (HOM) in the gas phase and relatively low volatility SOA dominated by C7-C10 species. We then use computational methods to develop the first stages of a Δ3-carene photochemical oxidation mechanism and explain some of our measured compositions. We find that alkoxy bond scission of the cyclohexyl ring likely leads to efficient HOM formation, in line with previous studies. We also find a surprising role for the abstraction of primary hydrogens from methyl groups, which has been calculated to be rapid in the α-pinene system, and suggest more research is required to determine if this is more general to other systems and a feature of autoxidation. This work develops a more comprehensive view of Δ3-carene photochemical oxidation products via measurements and lays out a suggested mechanism of oxidation via computationally derived rate coefficients. This dataset is not publicly accessible because: Non-EPA data. It can be accessed through the following means: Please contact Joel Thornton at: thornton@atmos.uw.edu. Format: text files. This dataset is associated with the following publication: D'Ambro, E., N. Hyttinen, K. Møller, S. Iyer, R. Otkjær, D. Bell, J. Liu, F. Lopez-Hilfiker, S. Schobesberger, J. Shilling, A. Zelenyuk, H. Kjaergaard, J. Thornton, and T. Kurten. Pathways to highly oxidized products in the Δ3-Carene + OH system. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, USA, 56(4): 2213-2224, (2022).

This dataset contains data presented in the figures of the paper "On the implications of aerosol liquid water and phase separation for organic aerosol mass" published in Atmospheric Chemistry and Physics. It also links to the data archive of field observations. This dataset is associated with the following publication: Pye, H., B. Murphy, L. Xu, N. Ng, A. Carlton, H. Guo, R. Weber, P. Vasilakos, W. Appel, S. Budisulistiorini, J. Surratt, A. Nenes, W. Hu, J. Jimenez, G. saacman-VanWertz, P. Misztal, and A. Goldstein. On the implications of aerosol liquid water and phase separation for organic aerosol mass. Atmospheric Chemistry and Physics. Copernicus Publications, Katlenburg-Lindau, GERMANY, 17: 343-369, (2017).

Dataset contains CMAQv5.3-predicted hourly average concentrations of organic aerosol and other species (HO2, NO, NO3, O3, OH) for Hyytiala, Finland (location of BAECC field campaign) and Centreville, AL, USA (main location of SOAS field campaign) for 2016. How species were created from raw CMAQ output is defined in Table S2 of the paper this data supports. CMAQ v5.3 code is also linked here. The specific configuration of CMAQ is described in the manuscript associated with this data. This dataset is associated with the following publication: Lee, B., E. D'Ambro, F. Lopez-Hilfiker, S. Schobesberger, C. Mohr, M. Zawakowicz, J. Liu, J. Shilling, W. Hu, B. Palm, J. Jimenez, L. Hao, A. Virtanen, H. Zhang, A. Goldstein, H. Pye, and J. Thornton. Resolving Ambient Organic Aerosol Formation and Aging Pathways with Simultaneous Molecular Composition and Volatility Observations. ACS Earth and Space Chemistry. American Chemical Society, Washington, DC, USA, 4(3): 391-402, (2020).

Dataset contains CMAQv5.3-predicted hourly average concentrations of organic aerosol and other species (HO2, NO, NO3, O3, OH) for Hyytiala, Finland (location of BAECC field campaign) and Centreville, AL, USA (main location of SOAS field campaign) for 2016. How species were created from raw CMAQ output is defined in Table S2 of the paper this data supports. CMAQ v5.3 code is also linked here. The specific configuration of CMAQ is described in the manuscript associated with this data. This dataset is associated with the following publication: Lee, B., E. D'Ambro, F. Lopez-Hilfiker, S. Schobesberger, C. Mohr, M. Zawakowicz, J. Liu, J. Shilling, W. Hu, B. Palm, J. Jimenez, L. Hao, A. Virtanen, H. Zhang, A. Goldstein, H. Pye, and J. Thornton. Resolving Ambient Organic Aerosol Formation and Aging Pathways with Simultaneous Molecular Composition and Volatility Observations. ACS Earth and Space Chemistry. American Chemical Society, Washington, DC, USA, 4(3): 391-402, (2020).