Direct Probing of Organic Peroxy Radical Autoxidation and Cross Reactions

University Of Washington, Seattle WA

Investigators

Abstract

This award is supported by the Environmental Chemical Sciences Program of the Division of Chemistry. Professor Joel Thornton of the University of Washington and his group investigate what happens to reactive organic carbon species in the Earth's atmosphere. The highly reactive organic peroxy radicals are common species produced when carbon-based (organic) compounds degrade in the environment. Their detection and quantification is difficult because of their reactivity. Often only a total of organic peroxy radicals are measured, or only early decomposition products are identified. This project involves novel laboratory studies of the reactivity of these species which provides more detailed information than previously possible. An accurate understanding of the fundamental pathways of environmental degradation is crucial to determining what happens to pollutants as they naturally cycle through the Earth's environment. Improved experimental data are necessary for understanding how fuel combustion impacts the atmosphere, aquatic ecosystems, and soil composition. The project provides educational and training opportunities for graduate students, undergraduates in chemistry and atmospheric sciences, and a postdoctoral research fellow. To inform the public of the results of this research, a computer animation is being produced in collaboration with a documentary filmmaker. This film shows how organic peroxy radicals produced in forests contribute to atmospheric particle formation and growth. This research is important to society as it promotes public health and understanding of weather and storms. This project uses fast flow tube reactors coupled to high resolution time of flight and orbitrap mass spectrometers. These techniques allow researchers to identify and simultaneously track nearly all individual organic peroxy radicals and their cross-reaction products. Reaction tracking of a suite of relevant starting compounds, purchased commercially or synthesized by collaborators, is done as a function of reaction time. These experiments provide quantitative insights into the rates and products of gas-phase organic carbon degradation under typical environmental conditions. Isotopic labeling and competitive reactant experiments allow for tests of hypothesized reaction mechanisms and independent rate quantification. 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.