Laboratory Studies of Ice Nucleation Using Optical and Raman Microscopy

将开发和使用新的实验室技术来探测冰的成核作用，并提高我们对对流层上层冰形成的理解。用于检测单个颗粒成冰的光学显微镜、用于确定化学成分的拉曼显微镜和低温湿度计将结合在一个设备中，以深入了解颗粒的化学和物理特性如何影响它们成核冰的能力。首先，我们将重新考察硫酸铵上的冰核。过去的工作表明，从硫酸铵水溶液中均匀成核所需的过饱和度分布很广。光学显微镜和拉曼显微镜的结合将被用来确定这是否由于不同相的硫酸铵的存在所致。其次，将开展有机物与无机物混合成冰的综合研究。现场观测显示，对流层上部存在大量的水过饱和现象，并表明有机物质在形成冰核的颗粒中可能没有得到充分的代表。将进行实验以分离成核的尺寸依赖关系和成分依赖关系。最后，我们将研究矿物和尘埃气溶胶上的冰核作用。拉曼探测器将提供对化学复杂颗粒在大气冰核形成中的作用的洞察。这些结果将有助于理解卷云的形成及其对气候的影响。该项目将为学生，特别是女性学生提供获得研究和教学技能的机会，这些技能将促进他们在大气化学和物理方面的科学生涯。

New laboratory techniques will be developed and used to probe ice nucleation and improve our understanding of ice formation in the upper troposphere. Optical microscopy to detect ice nucleation from individual particles, Raman microscopy to determine the chemical composition, and a cryogenic hygrometer will be combined in a single apparatus to gain insight into how the chemical and physical properties of the particles affect their ability to nucleate ice. First, ice nucleation on ammonium sulfate will be reexamined. Past work has indicated a wide spread in the supersaturation needed for homogeneous nucleation from aqueous ammonium sulfate. The combination of optical and Raman microscopy will be used to determine if this is due to the presence of different phases of ammonium sulfate. Second, a comprehensive study of ice nucleation on organics mixed with inorganics will be carried out. Field observations have shown large water supersaturations in the upper troposphere, and have suggested that organics may be underrepresented in particles that nucleate ice. Experiments will be performed to separate the size dependence of nucleation from the composition dependence. Finally, ice nucleation on mineral and dust aerosols will be examined. The Raman probe will provide insight into the role of chemically complex particles in atmospheric ice nucleation. The results will be useful in understanding cirrus cloud formation and its climatic impact. This project will give students, particularly women, the opportunity to gain skills in research and teaching that will further their scientific careers in atmospheric chemistry and physics.