RUI: Laboratory Studies of Particle Nucleation--Homogeneous Nucleation Involving Sulfuric Acid (H2SO4), Water (H2O), and Ammonia (NH3) Vapors

研究者将在流动反应器实验中测量新粒子的成核速率。新颗粒的形成速率将被测量为硫酸浓度、温度、相对湿度和氨浓度的函数。研究人员计划部署作为硫酸来源的蒸汽在散装液体和二氧化硫的原位氧化通过羟基自由基产生的光解作用。在二元系统中测量到较高的相对湿度和较低的温度，需要作为理解流动反应器内成核和评估理论模型的基线。光解系统将允许一个扩展的硫酸来源，平衡其损失到壁，促进成核结果的分析和解释。例如，它将允许可控暴露于颗粒生长剂，以便颗粒探测器可以有效地检测颗粒。扩展源也将允许在低硫酸浓度下探索成核。最后，需要对最近使用光解源的工作进行验证，该工作表明，与散装源的成核速率相比，成核速率提高了105倍或更多。这项工作将有助于了解大气中的成核以及它如何影响云凝结核的浓度，云凝结核在气候过程中的作用被认为是很大的，但仍然很不确定。了解大气颗粒的形成也很重要，因为吸入的颗粒物质对健康有害。流动反应器实验测量颗粒形成和生长的方法将进一步发展。在硫酸、水和氨系统中成核速率的结果将被合成，并将发展一个全面的实验室工作的画面。这将有助于解释现场数据和评价成核机制。该项目将通过为对环境科学感兴趣的本科生提供研究机会，加强奥格斯堡学院的研究和教育文化。这项工作是及时而重要的，这将培养学生对工作的奉献精神，并激发学生的想象力。该项目将通过提供：(a)高质量的工作经验，培养基本的实验室技能，(b)通过获得可能影响我们对全球变暖过程的理解的研究成果来增强动力，以及(c)提供在地方和国家会议上展示成果的机会，从而加强本科生培训。该项目将促进私立文理学院和公立研究型大学之间合作关系的延续，从而扩大奥格斯堡学院学生的学习和培训机会。预计女性和来自代表性不足群体的人将继续占PI实验室本科生的大多数。成果的传播将包括在地方和国家科学会议上的报告和手稿出版物。

The investigator will measure the rate of nucleation of new particles in flow reactor experiments. The formation rate of new particles will be measured as a function of sulfuric acid concentration, temperature, relative humidity and ammonia concentration. The researchers plan to deploy as sources of sulfuric acid both the vapor over the bulk liquid and in situ oxidation of sulfur dioxide via hydroxyl radical generated photolytically. Measurements in the binary system to higher relative humidities and to lower temperatures are needed as a baseline for understanding nucleation within the flow reactor and for evaluating theoretical models. The photolytic system will allow for an extended source of sulfuric acid that balances its loss to the wall, facilitating the analysis and interpretation of nucleation results. For example, it will allow for a controllable exposure to a particle growth agent so that particles can be efficiently detected by the particle detector. The extended source will also allow for exploration of nucleation at low sulfuric acid concentrations. Finally, verification is needed of recent work using a photolytic source that showed enhancements in the nucleation rate of factors of 105 or more over bulk source nucleation rates. This work will contribute to understanding nucleation in the atmosphere and how it influences the concentration of cloud condensation nuclei whose role in climate processes is believed to be large but is still quite uncertain. Understanding the formation of atmospheric particles is also important as inhaled particulate matter is a health hazard. Flow reactor experimental methods for measuring particle formation and growth will be further developed. Results for nucleation rates in the sulfuric acid, water, and ammonia systems will be synthesized and a comprehensive picture of laboratory work will be developed. This will aid interpretation of field data and evaluating mechanisms of nucleation.The project will enhance the research and the educational culture at Augsburg College by offering a research opportunity for undergraduates interested in the environmental sciences. The work is timely and important, which will foster a dedication to the work and fuel the student's imagination. The project will enhance undergraduate training by providing: (a) a high quality work experience where basic laboratory skills will be developed, (b) enhance motivation by obtaining research results that can affect our understanding of global warming processes, and (c) provide opportunities for presenting results at local and national meetings. This project will foster the continuation of the partnership between a private liberal arts college and a public research university, thereby expanding learning and training opportunities for Augsburg College's student population. It is expected that women and persons from underrepresented groups will continue to be the majority of the undergraduate students in the PI's lab. Dissemination of results will include presentations at local and national scientific meetings and manuscript publications.