An organic crystalline state in ageing atmospheric aerosol proxies: spatially resolved structural changes in levitated fatty acid particles
نویسندگان
چکیده
Abstract. Organic aerosols are key components of the Earth's atmospheric system. The phase state organic is known to be a significant factor in determining aerosol reactivity, water uptake and lifetime – with wide implications for cloud formation, climate, air quality human health. Unsaturated fatty acids contribute urban cooking emissions sea spray aerosols. These compounds, exemplified by oleic acid its sodium salt, surface-active have been shown self-assemble into variety liquid-crystalline phases upon addition water. Here we observe crystalline acid–soap complex acoustically levitated acid–sodium oleate particles. We developed synchrotron-based simultaneous small-angle wide-angle X-ray scattering (SAXS WAXS)–Raman microscopy system probe physical chemical changes proxy during exposure humidity oxidant ozone. present spatially resolved structural picture particle humidification, revealing gradient consisting disordered liquid shell core. Ozonolysis significantly slower compared phase, portion (34 ± 8 %) unreacted material remains after extensive oxidation. experimental evidence inert surface layer formation ozonolysis, taking advantage SAXS–WAXS experiments. observations suggest that lifetimes species highly phase-dependent, potentially impacting long-range transport pollutants such as polycyclic aromatic hydrocarbons (PAHs).
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ژورنال
عنوان ژورنال: Atmospheric Chemistry and Physics
سال: 2021
ISSN: ['1680-7316', '1680-7324']
DOI: https://doi.org/10.5194/acp-21-15003-2021