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

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.