Articles | Volume 25, issue 21 
            
                
                    
            
            
            https://doi.org/10.5194/acp-25-14301-2025
                    © Author(s) 2025. This work is distributed under 
the Creative Commons Attribution 4.0 License.
                the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/acp-25-14301-2025
                    © Author(s) 2025. This work is distributed under 
the Creative Commons Attribution 4.0 License.
                the Creative Commons Attribution 4.0 License.
Surface tension and hygroscopicity analysis of aerosols containing organosulfate surfactants
Vahid Shahabadi
                                            Department of Atmospheric and Oceanic Sciences, McGill University, Montreal, Quebec, Canada
                                        
                                    Cassandra Lefort
                                            Department of Chemistry, McGill University, Montreal, Quebec, Canada
                                        
                                    Hoi Tang Law
                                            Department of Earth and Environmental Science, Faculty of Science, The Chinese University of Hong Kong, Hong Kong, Hong Kong SAR, China
                                        
                                    Man Nin Chan
                                            Department of Earth and Environmental Science, Faculty of Science, The Chinese University of Hong Kong, Hong Kong, Hong Kong SAR, China
                                        
                                    Thomas C. Preston
CORRESPONDING AUTHOR
                                            
                                    
                                            Department of Atmospheric and Oceanic Sciences, McGill University, Montreal, Quebec, Canada
                                        
                                    
                                            Department of Chemistry, McGill University, Montreal, Quebec, Canada
                                        
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Donger Lai, Yanxin Bai, Zijing Zhang, Pui-Kin So, Yong Jie Li, Ying-Lung Steve Tse, Ying-Yeung Yeung, Thomas Schaefer, Hartmut Herrmann, Jian Zhen Yu, Yuchen Wang, and Man Nin Chan
                                    Atmos. Chem. Phys., 25, 12569–12584, https://doi.org/10.5194/acp-25-12569-2025, https://doi.org/10.5194/acp-25-12569-2025, 2025
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                                                Aqueous-phase •OH oxidation can potentially act as an important atmospheric sink for α-pinene-derived organosulfates (OSs). Such oxidation can also generate a variety of new OS products, and can be as a potential source for some atmospheric OSs with previously unknown origins.
                                            
                                            
                                        Xiangyu Pei, Yikan Meng, Yueling Chen, Huichao Liu, Yao Song, Zhengning Xu, Fei Zhang, Thomas C. Preston, and Zhibin Wang
                                    Atmos. Chem. Phys., 24, 5235–5246, https://doi.org/10.5194/acp-24-5235-2024, https://doi.org/10.5194/acp-24-5235-2024, 2024
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                                                An aerosol optical tweezer (AOT) Raman spectroscopy system is developed to capture a single aerosol droplet for phase transition monitoring and morphology studies. Rapid droplet capture is achieved and accurate droplet size and refractive index are retrieved. Results indicate that mixed inorganic/organic droplets are more inclined to form core–shell morphology when RH decreases. The phase transitions of secondary mixed organic aerosol/inorganic droplets vary with their precursors.
                                            
                                            
                                        Yueling Chen, Xiangyu Pei, Huichao Liu, Yikan Meng, Zhengning Xu, Fei Zhang, Chun Xiong, Thomas C. Preston, and Zhibin Wang
                                    Atmos. Chem. Phys., 23, 10255–10265, https://doi.org/10.5194/acp-23-10255-2023, https://doi.org/10.5194/acp-23-10255-2023, 2023
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                                                The impact of acidity on the phase transition behavior of levitated aerosol particles was examined. Our results revealed that lower acidity decreases the separation relative humidity of aerosol droplets mixed with ammonium sulfate and secondary organic aerosol proxy. Our research suggests that in real atmospheric conditions, with the high acidity found in many ambient aerosol particles, droplets encounter heightened impediments to phase separation and tend to display a homogeneous structure.
                                            
                                            
                                        Rani Jeong, Joseph Lilek, Andreas Zuend, Rongshuang Xu, Man Nin Chan, Dohyun Kim, Hi Gyu Moon, and Mijung Song
                                    Atmos. Chem. Phys., 22, 8805–8817, https://doi.org/10.5194/acp-22-8805-2022, https://doi.org/10.5194/acp-22-8805-2022, 2022
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                                                In this study, the viscosities of particles of sucrose–H2O, AS–H2O, and sucrose–AS–H2O for OIRs of 4:1, 1:1, and 1:4 for decreasing RH, were quantified by poke-and-flow and bead-mobility techniques at 293 ± 1 K. Based on the viscosity results, the particles of binary and ternary systems ranged from liquid to semisolid, and even the solid state depending on the RH. Moreover, we compared the measured viscosities of ternary systems to the predicted viscosities with excellent agreement.
                                            
                                            
                                        Rongshuang Xu, Sze In Madeleine Ng, Wing Sze Chow, Yee Ka Wong, Yuchen Wang, Donger Lai, Zhongping Yao, Pui-Kin So, Jian Zhen Yu, and Man Nin Chan
                                    Atmos. Chem. Phys., 22, 5685–5700, https://doi.org/10.5194/acp-22-5685-2022, https://doi.org/10.5194/acp-22-5685-2022, 2022
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                                                To date, while over a hundred organosulfates (OSs) have been detected in atmospheric aerosols, many of them are still unidentified, with unknown precursors and formation processes.  We found the heterogeneous OH oxidation of an α-pinene-derived organosulfate (C10H17O5SNa, αpOS-249, αpOS-249) can proceed at an efficient rate and transform into more oxygenated OSs, which have been commonly detected in atmospheric aerosols and α-pinene-derived SOA in chamber studies.
                                            
                                            
                                        Hang Yin, Jing Dou, Liviana Klein, Ulrich K. Krieger, Alison Bain, Brandon J. Wallace, Thomas C. Preston, and Andreas Zuend
                                    Atmos. Chem. Phys., 22, 973–1013, https://doi.org/10.5194/acp-22-973-2022, https://doi.org/10.5194/acp-22-973-2022, 2022
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                                                Iodine and carbonate species are important components in marine and dust aerosols, respectively. We introduce an extended version of the AIOMFAC thermodynamic mixing model, which includes the ions I−, IO3−, HCO3−, CO32−, OH−, and CO2(aq) as new species, and we discuss two methods for solving the carbonate dissociation equilibria numerically. We also present new experimental water activity data for aqueous iodide and iodate systems.
                                            
                                            
                                        Young-Chul Song, Joseph Lilek, Jae Bong Lee, Man Nin Chan, Zhijun Wu, Andreas Zuend, and Mijung Song
                                    Atmos. Chem. Phys., 21, 10215–10228, https://doi.org/10.5194/acp-21-10215-2021, https://doi.org/10.5194/acp-21-10215-2021, 2021
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                                                We report viscosity of binary mixtures of organic material / H2O and inorganic salts / H2O, as well as ternary mixtures of organic material / inorganic salts/ H2O, over the atmospheric relative humidity (RH) range. The viscosity measurements indicate that the studied mixed organic–inorganic particles range in phase state from liquid to semi-solid or even solid across the atmospheric RH range at a temperature of 293 K.
                                            
                                            
                                        Hoi Ki Lam, Rongshuang Xu, Jack Choczynski, James F. Davies, Dongwan Ham, Mijung Song, Andreas Zuend, Wentao Li, Ying-Lung Steve Tse, and Man Nin Chan
                                    Atmos. Chem. Phys., 21, 2053–2066, https://doi.org/10.5194/acp-21-2053-2021, https://doi.org/10.5194/acp-21-2053-2021, 2021
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                                                This work demonstrates that organic compounds present at or near the surface of aerosols can be subjected to oxidation initiated by gas-phase oxidants, such as hydroxyl radicals (OH). The heterogeneous reactivity is sensitive to their surface concentrations, which are determined by the phase separation behavior. This results of this work emphasize the effects of phase separation and potentially distinct aerosol morphologies on the chemical transformation of atmospheric aerosols.
                                            
                                            
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                Short summary
                    This research explores how organosulfate surfactants affect aerosol particles and their response to changes in relative humidity in the atmosphere. Using optical trapping and strong electric fields to investigate single particles, it is found that these surfactants can significantly lower surface tension, even in very small amounts. These findings are important for understanding how such particles influence cloud formation and properties like brightness.
                    This research explores how organosulfate surfactants affect aerosol particles and their response...
                    
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