EAGER: Development of Novel Chemical Ionization Detection of Peroxy Radicals for Fundamental Kinetics Experiments

在化学系环境化学科学项目的支持下，卡内基梅隆大学的Neil Donahue教授和他的团队将研究高活性有机分子，即过氧基，它是低层大气中化学和空气污染以及燃烧化学的核心。当任何有机化合物开始氧化时，就会形成过氧基，然后它们会与许多不同的物种反应，包括其他过氧基。此外，在分子氧存在的情况下，过氧自由基可以在自氧化过程中与自己发生反应。该项目旨在开发一种新的更好的方法来测量这种非常活跃但非常重要的化学物种。这在大气和燃烧化学界是一个长期存在的挑战。该奖项将在大气科学和分析化学的交界处提供跨学科的学生培训，重点是先进的质谱学技术开发。过氧基的化学成分非常丰富，它在确定有机氧化对污染甚至气候影响的后果方面发挥着关键作用，因为氧化产物有助于形成或生长大气颗粒物。目前测量过氧基和限制其反应速率的方法很少，本项目的重点是改进化学电离质谱学方法，以提供高灵敏和准确的测量。这可以通过直接检测特定的“试剂”离子与自由基形成簇时形成的离子，或者在仪器入口加入其他气体，将过氧基转化为其他物种，也可以通过化学电离质谱仪进行测量来完成。化学的复杂性使这成为一个高风险但非常重要的项目。如果成功，它将为详细的测量提供基础，以便更好地限制有机化合物在大气和燃烧系统中的命运和反应产物。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。

With support from the Environmental Chemical Sciences Program in the Division of Chemistry, Professor Neil Donahue and his team at Carnegie Mellon University will investigate highly reactive organic molecules known as peroxy radicals that lie at the heart of chemistry and air pollution in the lower atmosphere as well as combustion chemistry. Peroxy radicals are formed when any organic compound starts to oxidize, and they then react with many different species, including other peroxy radicals. Further, peroxy radicals can react with themselves in the presence of molecular oxygen in a process known as autoxidation. This project aims to develop a new and better way to measure this very reactive but very important chemical species. This has been a long-standing challenge in the atmospheric and combustion chemistry communities. The award will provide interdisciplinary student training at the interface of atmospheric science and analytical chemistry with an emphasis on advanced mass spectrometry technique development.The chemistry of the peroxy radical is very rich, and it plays a critical role in determining the consequences of organic oxidation for pollution and even for climate effects since oxidation products help to form or grow atmospheric particles. There are few methods to measure peroxy radicals and to constrain the rates of their reactions, and this project focuses on refining chemical ionization mass spectrometry approaches to provide highly sensitive and accurate measurements. This will be done either by direct detection of ions formed when specific "reagent" ions form clusters with the radicals or when other gases are added to the instrument inlet to convert the peroxy radicals into other species that can also be measured via chemical ionization mass spectrometry. The complexity of the chemistry makes this a high-risk but highly important project. If successful, it will provide the foundation for detailed measurements to provide better constraints on the fate and reaction products of organic compounds in the atmosphere and in combustion systems.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.