Viscous Organic Liquids and Catalysis of Atmospheric Ice Nucleation

该奖项由美国国家科学基金会化学部环境化学科学项目颁发，支持德克萨斯农工大学的莎拉·布鲁克斯教授。布鲁克斯教授和她的学生研究了二次有机气溶胶（SAO）在大气冰粒成核中的作用。最近的测量表明，目前关于有机气溶胶阶段和云形成特性的一些假设可能是不正确的。首先，对流层中的大部分SOA以粘稠的、相当自由流动的液态存在。其次，粘性有机气溶胶的存在代表了一种以前未被认识到的颗粒供应，这种颗粒能够导致云中冰晶的冻结。收集到的数据用于评估粘性相和延迟水扩散在大气冰成核过程中的作用。该项目还包括研究生、本科生和高中生的培训。在德州农工大学的夏季，高中生们参加全校范围内的TAMU青年冒险计划，参加讲座和实验室活动，包括“粘度在我们喜爱的食物中的作用”。该团队收集了代表性有机化合物和混合物的相、水扩散和冰成核能力的定量数据。样品气溶胶的相是由它们的温度依赖的粘度和温度，他们从液体转变为玻璃使用专门的光谱技术。此外，所有样品的冷冻温度都是使用我们定制的冰显微镜技术确定的。综上所述，这些数据用于评估粘性气溶胶是否存在最低玻璃化转变温度要求，以促进液滴的冻结。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award from the Environmental Chemical Sciences Program in the NSF Division of Chemistry supports Prof. Sarah Brooks at Texas A&M University. Prof. Brooks and her students study the role of secondary organic aerosols SAO) in the nucleation of atmospheric ice particles. Recent measurements indicate that several current assumptions about the organic aerosol phase and the cloud-forming properties may be incorrect. First, the majority of SOA in the troposphere exist in a viscous, rather free-flowing liquid state. Second, the presence of viscous organic aerosols represents a previously unrecognized supply of particles capable of causing the freezing of ice crystals in clouds. The data collected are used to assess the role of viscous phases and retarded water diffusion in atmospheric ice nucleation processes. The project also includes the training of graduate students, undergraduate students, and high school students. During summers at Texas A&M, high school students attend the campus-wide TAMU Youth Adventure Program to participate in lecture and laboratory activities including, "The role of viscosity in the foods we love." The team collects quantitative data on the phase, water diffusion, and ice nucleating ability of representative organic compounds and mixtures. The phases of sample aerosols are characterized by their temperature-dependent viscosities and the temperature at which they transition from liquid to glass using specialized spectroscopic techniques. In addition, the freezing temperatures of all samples are determined using our custom ice microscope technique. Taken together the data are used to evaluate whether a minimum glass transition temperature requirement exists for viscous aerosol to facilitate the freezing of droplets.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.