Cloud condensation nuclei (CCN) activation is sensitive to the size, composition, and morphology of aerosol particles < 200 nm. By controlling the particle morphology of internally mixed samples (i.e. homogeneous vs. phase separated), we have probed the effect of morphology on CCN activity using model organic aerosol systems, where ammonium sulfate was mixed with either pimelic acid or succinic acid in a 50/50 mixture by weight. Surprisingly, for systems of the same composition, but distinct morphology, we observe a noticeable impact on CCN activity. Specifically, a phase separated morphology results in activation diameters close to that of ammonium sulfate, while a homogeneous morphology yields an activation diameter in between the pure inorganic and organic components. Our results suggest that morphology-resolved CCN data may be an important parameter to consider in cloud microphysics models to improve predictions of CCN activity of complex organic aerosols. For laboratory CCN studies, it is important to control or account for atomized solution drying rates which have been shown to affect morphology and ultimately CCN activity.

中文翻译：

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粒子形态对云凝结核活性的影响

云凝结核（CCN）激活对<200 nm的气溶胶颗粒的大小，组成和形态很敏感。通过控制内部混合样品的颗粒形态（即均相与相分离），我们使用模型有机气溶胶系统探究了形态对CCN活性的影响，其中硫酸铵与庚二酸或琥珀酸以50 /按重量计50种混合物。出乎意料的是，对于组成相同但形态不同的系统，我们观察到对CCN活性的显着影响。具体地，相分离的形态导致活化直径接近硫酸铵的活化直径，而均匀的形态产生介于纯无机和有机组分之间的活化直径。我们的结果表明，形态学解析的CCN数据可能是云微物理模型中要考虑的一个重要参数，以改善对复杂有机气溶胶CCN活性的预测。对于实验室CCN研究，控制或考虑雾化溶液的干燥速率非常重要，这已证明会影响形态并最终影响CCN活性。