Hygroscopic Properties of Microstructured Aerosols

在其生命周期中，来自不同来源的环境气溶胶除了通过冷凝和化学反应等不同的过程进行改变外，还与其他气溶胶或云滴发生凝结。这些过程导致形成具有复杂微结构的气溶胶，其中包括分散在液滴中的固体颗粒，或分层颗粒。气溶胶微结构通过改变其在大气物理、化学和辐射过程中的作用，在确定其对气候的影响方面发挥着重要作用。目前，还没有可用于微结构气溶胶的体积、时间和空间分辨物理化学表征的技术。实验将在具有各种类型微结构的单个纳米颗粒上进行。将测试不同的方法来产生具有不同选择特性的纳米颗粒。其中一类颗粒，表面涂层为各种化合物的烟尘颗粒，将在受控环境下悬浮在电动平衡中。随着环境湿度和温度的变化，将观察这些颗粒，以评估这些覆盖有亲水和疏水化合物的碳烟纳米颗粒的吸湿性能，以及这些性能如何随着不同涂层的化学成分和物理布置的变化而变化。该项目将与慕尼黑理工大学的莱因哈德·尼斯纳教授合作进行。这项工作的成功完成将为未来探索这些气溶胶的光学性质随着环境条件的变化而变化奠定基础。该项目的智力优势在于开发了研究在大气过程和气候中发挥重要作用的微结构气溶胶的新工具。拟议的研究要取得成功，就必须了解与微结构烟尘气溶胶有关的物理和化学过程。该研究将为研究生提供非传统化学工程方面的实验室培训，并为他/她提供国际研究经验。该项目的研究知识将对本科生和研究生教育产生影响。此外，高中生还将接触到这项研究的某些方面。

During their lifetime, ambient aerosols from various sources coagulate with other aerosols or cloud droplets, in addition to undergoing alteration through heterogeneous processes, such as condensation and chemical reactions. These processes lead to the formation of aerosols with complex microstructures that include solid particles dispersed in liquid droplets, or layered particles. Aerosol microstructures play a significant role in determining their climatic impact by altering their role in atmospheric physical, chemical and radiative processes. Currently, no technique is available for volumetric time and space-resolved physical and chemical characterization of microstructured aerosols.Experiments will be conducted on single nanoparticles manufactured to have various types of microstructures. Different methods will be tested for generating nanoparticles with various chosen properties. One class of these particles, soot particles with surface coatings of various compounds, will be suspended in electrodynamic balances under controlled environments. The particles will be observed as environmental humidity and temperature are varied to evaluate hygroscopic properties of these soot nanoparticles coated with hydrophilic and hydrophobic compounds, and how these properties vary with variation in chemical components and physical arrangements of the various coatings. This project will be conducted in collaboration with Prof. Reinhard Niessner of Technische Universitaet Muenchen. Successful completion of this work will lay the foundation for future exploration of variation of optical properties of these aerosols as environmental conditions vary.The intellectual merits of the project lie in the development of new tools for studying microstructured aerosols that play significant roles in atmospheric processes and climate. A successful outcome of the proposed research will be critically needed understanding of physical and chemical processes associated with microstructured soot aerosols. The research will provide laboratory training for a graduate student in non-traditional chemical engineering aspects, as well as provide him/her with an international research experience. The research knowledge from the project will impact both undergraduate and graduate education. In addition, high school students will be exposed to some aspects of the research.