Direct measurements of semi-volatile organic compound dynamics show near-unity mass accommodation coefficients for diverse aerosols

Liu, Xiaoxi; Day, Douglas A.; Krechmer, Jordan E.; Brown, Wyatt L.; Peng, Zhe; Ziemann, Paul J.; Jimenez, José L.

doi:10.1038/s42004-019-0200-x

Cited by 66 publications

(101 citation statements)

References 69 publications

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“…Among these three methods using CIMS measurements of organic acids, Stark et al (2017) note that the result from the thermogram method is more consistent with those measured by an aerosol mass spectrometer (AMS) with a thermo denuder (TD), which also applied the thermogram method to estimate the C * distributions (Hu et al, 2016). Saha et al (2017) applied an evaporation kinetic model (Lee et al, 2011) based on the VBS approach to extract the C * distributions, and the effects of enthalpy of vaporization (△Hvap) and accommodation coefficient (α) are considered, resulting in the estimated Tg,org of 313 K. This study retrieved α ~0.5, which is consistent with recent observations (Krechmer et al, 2017;Liu et al, 2019). In summary, Tg,org during the SOAS campaign span the range of 313 -330 K. et al, 2019), which may be due to substantial formation of organosulfates and other oligomers (Lin et al, 2012;Hu et al, 2015;Riva et al, 2019).The predicted Tg,org of IEPOX-SOA is higher than previously reported Tg,org of 263 -293 K for monoterpenederived (α-pinene, △ 3 -carene, myrcene, limonene and ocimene) SOA (Petters et al, 2019).…”

Section: Southern Oxidant and Aerosol Study (Soas)supporting

confidence: 86%

Predictions of the glass transition temperature and viscosity of organic aerosols by volatility distributions

Liu¹,

Day²,

Stark³

et al. 2020

Preprint

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Abstract. Volatility and viscosity are important properties of organic aerosols (OA), affecting aerosol processes such as formation, evolution and partitioning of OA. Volatility distributions of ambient OA particles have often been measured, while viscosity measurements are scarce. We have previously developed a method to estimate glass transition temperature (Tg) of an organic compound containing carbon, hydrogen, and oxygen. Based on analysis of over 2300 organic compounds including oxygenated organic compounds as well as nitrogen- and sulfur-containing organic compounds, we extend this method to include nitrogen- and sulfur-containing compounds based on elemental composition. In addition, parameterizations are developed to predict Tg as a function of volatility and the atomic oxygen-to-carbon ratio based on a negative correlation between Tg and volatility. The prediction method of Tg and viscosity is applied to ambient observations of volatility distributions at eleven field sites. The predicted Tg varies mainly from 290 K to 339 K and the predicted viscosities are consistent with the results of ambient particle phase state measurements in the southeastern US and the Amazonian rain forest. Reducing the uncertainties in measured volatility distributions would be helpful to improve predictions of viscosity especially at low relative humidity. We also predict the Tg of OA components identified via positive matrix factorization of aerosol mass spectrometer data. The predicted viscosity of oxidized OA is consistent with previously reported viscosity of SOA derived from α-pinene, toluene, isoprene epoxydiol (IEPOX), and of diesel fuel. Comparison of the predicted viscosity based on the observed volatility distributions with the viscosity simulated by a chemical transport model implies that missing low volatility compounds in a global model can lead to underestimation of OA viscosity at some sites. The relation between volatility and viscosity can be applied in the molecular corridor or volatility basis set approaches to improve OA simulations in chemical transport models by consideration of effects of particle viscosity in OA formation and evolution.

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Section: Southern Oxidant and Aerosol Study (Soas)supporting

confidence: 86%

Predictions of the glass transition temperature and viscosity of organic aerosols by volatility distributions

Liu¹,

Day²,

Stark³

et al. 2020

Preprint

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“…These results are shown in Table 4. Note that this is less than the general average for many studied aerosol (∼0.9) and specifically for the similar compound toluene, which was determined to be 0.3 ≤ α p ≤ 0.6 (Liu et al, 2019).…”

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confidence: 74%

Secondary Organic Aerosol Yields from the Oxidation of Benzyl Alcohol

Charan¹,

Buenconsejo²,

Seinfeld³

2020

Preprint

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Abstract. Recent inventory-based analysis suggests that emissions of volatile chemical products in urban areas are now competitive with those from the transportation sector. Understanding the potential for secondary organic aerosol formation from these volatile chemical products is, therefore, critical to predicting levels of aerosol and for formulating policy to reduce aerosol exposure. It is clear that a plethora of oxygenated compounds are either emitted directly into the atmosphere or emitted indoors and later escape into the outdoors. Experimental and computationally simulated environmental chamber data provide an understanding of aerosol yield and chemistry under relevant urban conditions (5–200 ppb NO and 291–312 K) and give insight into the effect of volatile chemical products on the production of secondary organic aerosol. Benzyl alcohol, one of these volatile chemical products, is found to have a large secondary organic aerosol formation potential. At NO concentrations of ~ 80 ppb and 291 K, secondary organic aerosol mass yields for benzyl alcohol can reach 1.

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“…As In order to assess effects on the sulfate fragmentation from mixing with OA, chamber experiments, where different types of SOA were formed by gas-phase reactions and condensation onto AS seeds, were investigated. SOA was formed from alkanol and toluene photooxidation under high-NO x conditions (Liu et al, 2019) , as well as Δ-3-carene and -pinene reactions with nitrate radicals (Kang et al, 2016) Experiments were initiated with 100% AS in a dry chamber (RH < 5%; ~ 298 K) followed by either rapid, gradual, or stepwise increases of SOA until a maximum OA/(OA+AS) ratio of ~ 70% was reached. Aerosol composition was monitored by AMS and size distributions were monitored with a scanning mobility particle sizer (SMPS, TSI).…”

Section: Laboratory Experimentsmentioning

confidence: 99%

Aerosol pH Indicator and Organosulfate Detectability from Aerosol Mass Spectrometry Measurements

Schueneman¹,

Nault²,

Campuzano‐Jost³

et al. 2020

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Abstract. Aerosol sulfate is a major component of submicron particulate matter (PM1). Sulfate can be present as inorganic (mainly ammonium sulfate, AS) or organic sulfate (OS). Although OS are thought to be a smaller fraction of total sulfate in most cases, recent literature argues that this may not be the case in more polluted environments. Aerodyne Aerosol Mass Spectrometers (AMS) measure total submicron sulfate, but it has been difficult to apportion AS vs. OS as the detected ion fragments are similar. Recently, two new methods have been proposed to quantify OS separately from AS with AMS data. We use observations collected during several airborne field campaigns covering a wide range of sources and airmass ages (spanning the continental US, marine remote troposphere, and Korea) and targeted laboratory experiments to investigate the performance and validity of the proposed OS methods. Four chemical regimes are defined to categorize the factors impacting sulfate fragmentation (Fig. shown in abstract). In polluted areas with high ammonium nitrate concentrations and in remote areas with high aerosol acidity, the decomposition and fragmentation of sulfate in the AMS is influenced by multiple complex effects, and estimation of OS does not seem possible with current methods. In regions with lower acidity (pH>0) and ammonium nitrate (fraction<0.3), the proposed OS methods might be more reliable, although application of these methods often produced nonsensical results. However, the fragmentation of ambient neutralized sulfate varies somewhat within studies, adding uncertainty, possibly due to variations in the effect of organics. Under highly acidic conditions, sulfate fragment ratios show a clear relationship with acidity (pH and ammonium balance). The measured ammonium balance (and to a lesser extent, the HySOx+/SOx+ AMS ratio) is a promising indicator for rapid estimation of aerosol pH < 0, including when gas-phase NH3 and HNO3 are not available. These results allow an improved understanding of important intensive properties of ambient aerosols.

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Direct measurements of semi-volatile organic compound dynamics show near-unity mass accommodation coefficients for diverse aerosols

Cited by 66 publications

References 69 publications

Predictions of the glass transition temperature and viscosity of organic aerosols by volatility distributions

Predictions of the glass transition temperature and viscosity of organic aerosols by volatility distributions

Secondary Organic Aerosol Yields from the Oxidation of Benzyl Alcohol

Aerosol pH Indicator and Organosulfate Detectability from Aerosol Mass Spectrometry Measurements

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