Direct Surface Tension Measurements of Individual Sub-Micrometer Particles Using Atomic Force Microscopy

Lee, Hansol D.; Estillore, Armando D.; Morris, Holly S.; Ray, Kamal K.; Alejandro, Aldair; Grassian, Vicki H.; Tivanski, Alexei V.

doi:10.1021/acs.jpca.7b04041

Cited by 56 publications

(98 citation statements)

References 45 publications

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“…Since then, AFM has been used, most often in tandem with other analysis techniques, to characterize aerosol mixing state in urban and marine‐influenced urban environments (Sobanska et al, ; Vester et al, ), as well as during Chinese wintertime haze events (Chen et al, ). More recently, AFM studies have incorporated more detailed analysis of specific properties, such as surface tension (Lee et al, , ) and hygroscopicity (Ghorai et al, ; Morris et al, ). An exciting advancement for AFM has been coupling with a scanning IR laser to conduct photothermal IR spectroscopy (Bondy et al, ; Kwon et al, ; Or et al, ).…”

Section: Measurement Techniques For Aerosol Mixing Statementioning

confidence: 99%

Aerosol Mixing State: Measurements, Modeling, and Impacts

Riemer

Ault

West

et al. 2019

Reviews of Geophysics

271

287

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Atmospheric aerosols are complex mixtures of different chemical species, and individual particles exist in many different shapes and morphologies. Together, these characteristics contribute to the aerosol mixing state. This review provides an overview of measurement techniques to probe aerosol mixing state, discusses how aerosol mixing state is represented in atmospheric models at different scales, and synthesizes our knowledge of aerosol mixing state's impact on climate‐relevant properties, such as cloud condensation and ice nucleating particle concentrations, and aerosol optical properties. We present these findings within a framework that defines aerosol mixing state along with appropriate mixing state metrics to quantify it. Future research directions are identified, with a focus on the need for integrating mixing state measurements and modeling.

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Section: Measurement Techniques For Aerosol Mixing Statementioning

confidence: 99%

Aerosol Mixing State: Measurements, Modeling, and Impacts

Riemer

Ault

West

et al. 2019

Reviews of Geophysics

271

287

View full text Add to dashboard Cite

show abstract

“…The setup utilized a flow-through reactor to provide the reactive uptake coefficient of ozone on catechol films [61] under variable humidity conditions, and elucidated the formation of quinones as well as biphenyl and terphenyl rings [61]. Present and future laboratory, chamber, and field studies to examine the product mixtures resulting from these mechanisms are being inspired [152][153][154][155][156][157][158][159][160][161][162][163] by this work, to gather information for inclusion in the next generation of computational models to predict the effects of aerosols on climate.…”

Section: Outcomes Learned From Recent Interfacial Studiesmentioning

confidence: 99%

An Overview of Dynamic Heterogeneous Oxidations in the Troposphere

Pillar-Little

Guzmán

2018

Environments

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Due to the adverse effect of atmospheric aerosols on public health and their ability to affect climate, extensive research has been undertaken in recent decades to understand their sources and sinks, as well as to study their physical and chemical properties. Atmospheric aerosols are important players in the Earth’s radiative budget, affecting incoming and outgoing solar radiation through absorption and scattering by direct and indirect means. While the cooling properties of pure inorganic aerosols are relatively well understood, the impact of organic aerosols on the radiative budget is unclear. Additionally, organic aerosols are transformed through chemical reactions during atmospheric transport. The resulting complex mixture of organic aerosol has variable physical and chemical properties that contribute further to the uncertainty of these species modifying the radiative budget. Correlations between oxidative processing and increased absorptivity, hygroscopicity, and cloud condensation nuclei activity have been observed, but the mechanisms behind these phenomena have remained unexplored. Herein, we review environmentally relevant heterogeneous mechanisms occurring on interfaces that contribute to the processing of aerosols. Recent laboratory studies exploring processes at the aerosol–air interface are highlighted as capable of generating the complexity observed in the environment. Furthermore, a variety of laboratory methods developed specifically to study these processes under environmentally relevant conditions are introduced. Remarkably, the heterogeneous mechanisms presented might neither be feasible in the gas phase nor in the bulk particle phase of aerosols at the fast rates enabled on interfaces. In conclusion, these surface mechanisms are important to better understand how organic aerosols are transformed in the atmosphere affecting the environment.

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“…The importance of surface tension depression, however, remains contentious given the difficulty in quantifying surface tension in microscopic droplets directly (Broekhuizen et al, 2004(Broekhuizen et al, , 2006Mircea et al, 2005;Henning et al, 2005;Wex et al, 2009;Gray Bé et al, 2017;Good et al, 2010a, b;Jurányi et al, 2010;Fuentes et al, 2011;Duplissy et al, 2008;Prisle et al, 2011;Petters and Kreidenweis, 2013;Sareen et al, 2013;Giordano et al, 2013;Moore et al, 2008;Li et al, 1998). Surface tension reductions have been observed in macroscopic solutions of organic matter extracted form aerosols when the organic concentration is sufficiently large (Facchini et al, 1999;Noziere et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Establishing the impact of model surfactants on cloud condensation nuclei activity of sea spray aerosol mimics

et al. 2018

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Surface-active compounds present in aerosols can increase their cloud condensation nuclei (CCN) activation efficiency by reducing the surface tension (σ ) in the growing droplets. However, the importance of this effect is poorly constrained by measurements. Here we present estimates of droplet surface tension near the point of activation derived from direct measurement of droplet diameters using a continuous flow streamwise thermal gradient chamber (CFSTGC). The experiments used sea spray aerosol (SSA) mimics composed of NaCl coated by varying amounts of (i) oleic acid, palmitic acid or myristic acid, (ii) mixtures of palmitic acid and oleic acid, and (iii) oxidized oleic acid. Significant reductions in σ relative to that for pure water were observed for these mimics at relative humidity (RH) near activation ( ∼ 99.9 %) when the coating was sufficiently thick. The calculated surface pressure (π = σ H 2 O − σ observed ) values for a given organic compound or mixture collapse onto one curve when plotted as a function of molecular area for different NaCl seed sizes and measured RH. The observed critical molecular area (A 0 ) for oleic acid determined from droplet growth was similar to that from experiments conducted using macroscopic solutions in a Langmuir trough. However, the observations presented here suggest that oleic acid in microscopic droplets may exhibit larger π values during monolayer compression. For myristic acid, the observed A 0 compared well to macroscopic experiments on a fresh subphase, for which dissolution has an important impact. A significant kinetic limitation to water uptake was observed for NaCl particles coated with pure palmitic acid, likely as a result of palmitic acid (with coating thicknesses ranging from 67 to 132 nm) being able to form a solid film. However, for binary palmitic-acid-oleic-acid mixtures there was no evidence of a kinetic limitation to water uptake. Oxidation of oleic acid had a minor impact on the magnitude of the surface tension reductions observed, potentially leading to a slight reduction in the effect compared to pure oleic acid. A CCN counter was also used to assess the impact on critical supersaturations of the substantial σ reductions observed at very high RH. For the fatty-acid-coated NaCl particles, when the organic fraction (ε org ) was > 0.90 small depressions in critical supersaturation were observed. However, when ε org < 0.90 the impact on critical supersaturation was negligible. Thus, for the fatty acids considered here, the substantial σ reductions observed at high RH values just below activation have limited impact on the ultimate critical supersaturation. A surface film model is used to establish the properties that surface-active organic molecules must have if they are to ultimately have a substantial impact on the activation efficiency of SSA. To influence activation, the average properties of surface-active marine-derived organic molecules must differ substantially from the long-chain fatty acids examined, having either smaller molecular volumes o...

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Direct Surface Tension Measurements of Individual Sub-Micrometer Particles Using Atomic Force Microscopy

Cited by 56 publications

References 45 publications

Aerosol Mixing State: Measurements, Modeling, and Impacts

Aerosol Mixing State: Measurements, Modeling, and Impacts

An Overview of Dynamic Heterogeneous Oxidations in the Troposphere

Establishing the impact of model surfactants on cloud condensation nuclei activity of sea spray aerosol mimics

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