Oxidation Pathways and Radicals at the Gas-Particle Interface Using Surface-Sensitive Techniques

在这个项目中，首席研究员（PI）建议通过新方法与现有方法相结合来研究二级有机颗粒氧化机制。这些新的分析技术包括基质辅助电离质谱法（MAI-MS）和简易环境声波喷雾电离质谱法（EASI-MS），它们可以直接测量有机颗粒表面。这项工作建立在以前开发的测量技术的基础上，以研究影响有机气溶胶氧化的表面水平过程，这是一个已知的知识差距。这个项目的成功将填补这一空白，并可能对我们对气溶胶过程和大气化学的理解产生潜在的革命性改进。该项目包括对博士后研究员以及研究生和本科生的支持，并包括广泛的社区教育和外展。这些技术将通过三个特定目标应用于有机颗粒的非均相羟基自由基氧化前后：(1)利用MAI-MS和EASI-MS技术阐明过氧化物和其他表面结合产物的形成对反应物结构和氧化剂浓度的普遍性和敏感性；(2)利用自旋阱化合物直接观察高粘性模型粒子中的有机自由基，并在氮氧化物存在下间接测定过氧自由基的命运；(3)可以通过固体有机基质颗粒的吸收来测定哪些产物是由复杂的芳香族氧化产生的。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。

In this project, the Principal Investigator (PI) suggests studying secondary organic particle oxidation mechanisms via new approaches paired with established approaches. These novel analytical techniques include Matrix Assisted Ionization Mass Spectrometry (MAI-MS) and Easy Ambient Sonic-spray Ionization Mass Spectrometry (EASI-MS) which enable direct measurements of organic particle surfaces. This work builds upon previously developed measurement techniques in order to study the surface-level processes that impact organic aerosol oxidation, which is a known knowledge gap. Success in this project will fill this gap and could result in potentially transformative improvements to our understanding of aerosol processes and atmospheric chemistry. This project includes support for a postdoctoral researcher as well as graduate and undergraduate students and includes extensive community education and outreach.These techniques will be applied before and after heterogeneous hydroxy radical oxidation of organic particles via three specific objectives: (1) the elucidation of the universality and sensitivity of the formation of peroxides and other surface-bound products to reactant structures and oxidant concentrations using MAI-MS and EASI-MS techniques; (2) the direct observations of organic radicals in highly viscous model particles using spin trap compounds and the indirect determination of peroxy radical fate in the presence of nitrogen oxide; (3) the determination of which products that result from complex aromatic oxidations can be measured via uptake onto solid organic matrix particles.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.