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Liquid-Liquid Phase Separation in Single Suspended Aerosol Microdroplets.
1Key Laboratory for the Physics and Chemistry of Nanodevices, School of Electronics, Peking University, Beijing 100871, China.
Analytical Chemistry
|August 9, 2023
Summary
Liquid-liquid phase separation (LLPS) in aerosols impacts atmospheric processes. This study uses laser tweezers to show how acidity and salts influence LLPS in individual aerosol microdroplets.
Area of Science:
- Atmospheric Chemistry
- Physical Chemistry
- Spectroscopy
Background:
- Liquid-liquid phase separation (LLPS) is a common phenomenon in ambient aerosols.
- LLPS significantly affects aerosol physicochemical properties and atmospheric processes like mass transfer and heterogeneous reactions.
- Studying LLPS in individual, suspended aerosols is challenging due to experimental limitations.
Purpose of the Study:
- To investigate LLPS in individual contactless microdroplets.
- To understand the dynamic morphological transformations of aerosols during humidity cycles.
- To explore the influence of pH and inorganic components on aerosol LLPS.
Main Methods:
- Utilized a self-constructed laser tweezer/Raman spectroscopy system.
- Optically trapped individual microdroplets to mimic suspended aerosols.
- Employed time-resolved cavity-enhanced Raman spectroscopy to monitor dynamic changes.
Main Results:
- Observed dynamic morphological transformations of optically trapped droplets under humidity cycles.
- Found that increased acidity enhances miscibility and lowers the separation relative humidity.
- Demonstrated that inorganic components impact aerosol phase state based on their salting-out abilities.
Conclusions:
- LLPS in individual aerosols can be studied using laser tweezer/Raman spectroscopy.
- Acidity and inorganic salts play crucial roles in modulating aerosol LLPS.
- Findings have implications for understanding the morphology of atmospheric particles, especially mixed inorganic-organic aerosols.
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