Morphology of Organic/Inorganic Aerosol with Varying Seed Particle Water Content
Morphology of Organic/Inorganic Aerosol with Varying Seed Particle Water Content
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DOI：
10.1021/acsearthspacechem.3c00202
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发表时间：
2023-09
影响因子：
3.4
通讯作者：
Emma C. Tackman;Devon N. Higgins;Murray V. Johnston;M. Freedman
中科院分区：
文献类型：
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作者：
Emma C. Tackman;Devon N. Higgins;Murray V. Johnston;M. Freedman
混合有机/无机颗粒的形态可以强烈影响气溶胶的物理化学性质，但在颗粒形成研究中仍然相对较少。用α-蒎烯或柠檬烯二级有机气溶胶（SOA）在流动管反应器中培养的无机种子颗粒的形态与种子颗粒初始含水量有关。在低相对湿度（<15% RH，干燥）和高相对湿度（~ 60% RH，潮湿）条件下均可产生浮肿和潮解的硫酸铵种子颗粒，并在低生长和高生长条件下被二次有机物质包裹。对颗粒进行干燥，并使用扫描迁移率粒度谱法和透射电镜分析直径和底物引起的直径变化以及有机包覆颗粒的相分离率。脱肿后的无机种子颗粒直径普遍增大，而脱水后的无机种子颗粒直径差异较小，尽管它们在形态上与脱肿后的种子颗粒相似。溶解种子颗粒直径变化的差异表明，在RH循环过程中晶体结构发生了重构。在低有机生长条件下，soa包覆颗粒的直径呈负变化，湿种有机颗粒的直径变化幅度大于干种有机颗粒。高有机生长给干种子和湿种子样品带来了广泛的直径百分比差异。有有机涂层的湿种子颗粒偶尔会表现出干种子涂层颗粒所没有的纹理形态。使用流动管反应器结合光谱和显微镜技术，可以深入了解气溶胶颗粒形态对两种种子条件和两种二级有机前体形成参数的依赖性。
The morphology of mixed organic/inorganic particles can strongly influence the physicochemical properties of aerosols but remains relatively less examined in particle formation studies. The morphologies of inorganic seed particles grown with either α-pinene or limonene secondary organic aerosol (SOA) generated in a flow tube reactor were found to depend on initial seed particle water content. Effloresced and deliquesced ammonium sulfate seed particles were generated at low relative humidity (<15% RH, dry) and high relative humidity (∼60% RH, wet) and were also coated with secondary organic material under low growth and high-growth conditions. Particles were dried and analyzed using scanning mobility particle size spectrometry and transmission electron microscopy for diameter and substrate-induced diameter changes and for the prevalence of phase separation for organic-coated particles. Effloresced inorganic seed particle diameters generally increased after impaction, whereas deliquesced inorganic seed particles had smaller differences in diameter, although they appeared morphologically similar to the effloresced seed particles. Differences in the changes to diameter for deliquesced seed particles suggest crystal restructuring with RH cycling. SOA-coated particles showed negative diameter changes for low organic growth, although wet-seeded organic particles changed by larger magnitudes compared to dry-seeded organic particles. High organic growth gave wide-ranging diameter percent differences for both dry- and wet-seeded samples. Wet-seeded particles with organic coatings occasionally showed a textured morphology unseen in the coated particles with dry seeds. Using a flow tube reactor with a combination of spectrometry and microscopy techniques allowed for insights into the dependence of aerosol particle morphology on formation parameters for two seed conditions and two secondary organic precursors.