Collaborative Research: Exploring the Role of Organics in Atmospheric Contact Nucleation

该项目致力于研究大气中混合相云中冰粒的形成机制。这种机制被称为接触成核，当冰核粒子与过冷的云滴表面相撞时就会发生。这项研究的结果将提高模拟地球大气中的粒子和云的能力。这项研究将检验以下假设：(1)有机粒子可以作为接触核促进有机-无机混合水滴的风化，有机粒子的有效性将取决于水相的组成；温度和相对湿度；以及接触核的组成、氧化、粘度、形态和大小；以及(2)有机粒子可以作为接触核促进冰核的形成，有机粒子的有效性将取决于水相的组成；温度；以及接触核的组成、氧化、粘度、形态和大小。这些实验将使用两种互补的悬浮技术进行，这两种技术允许自由漂浮的液滴与定义明确的接触核进行单一碰撞：长工作距离光学陷阱和双阶段电动平衡。这些研究有望提供目前文献中无法获得的接触成核的基础数据。这项工作将改进非均相成核的理论描述，并使接触成核能够包括在预测大气中冰粒形成的大气模型中。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This project is focused on the study of a mechanism for the formation of ice particles in mixed phase clouds in the atmosphere. This mechanism, called contact nucleation, occurs when an ice nucleating particle collides with the surface of a supercooled cloud droplet. The results of this research will improve the ability to model particles and clouds in the Earth's atmosphere.The research will test the following hypotheses: (1) Organic particles can act as contact nuclei to promote efflorescence of mixed organic-inorganic aqueous droplets, and the effectiveness of the organic will depend on composition of the aqueous phase; temperature and relative humidity; and composition, oxidation, viscosity, morphology, and size of the contact nuclei; and (2) Organic particles can act as contact nuclei to promote ice nucleation, and the effectiveness of the organic will depend on composition of the aqueous phase; temperature; and composition, oxidation, viscosity, morphology, and size of the contact nuclei. The experiments will be conducted using two complementary levitation techniques that allow freely-floating droplets to undergo single collisions with well-defined contact nuclei: a long working distance optical trap and a dual stage electrodynamic balance.These studies are expected to provide fundamental data on contact nucleation that currently are not available in the literature. This effort will lead to improved theoretical descriptions of heterogeneous nucleation and enable contact nucleation to be included in atmospheric models that predict the formation of ice particles in the atmosphere.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.