In this project funded by the Environmental Chemical Sciences program of the Chemistry Division at the National Science Foundation, Professor Mitchio Okumura of the California Institute of Technology is researching the oxidation mechanisms of volatile organic compounds that form air pollution. Professor Okumura will provide excellent training for his graduate students utilizing modern experimental physical tools, as well as with scientific reasoning. They will utilize fast laser spectroscopic techniques to detect free radical species and observe how changes occur as they flow through atmospheric oxidation processes. The award will contribute to building the nation's scientific infrastructure through collaborations within the university, among three other universities, and two government funded research laboratories. International collaboration will also be expanded with individuals from the French National Synchrotron. Professor Okumura has a proven record in encouraging the participation of women and underrepresented minorities, which will be strengthened through outreach to underrepresented groups by the expansion of formal connections to classrooms in local K-12 schools. Prior outreach programs created by the Okumura Group will continue to be developed to teach elementary school students about air pollution while inspiring their interest in science.
This work focuses on characterizing the fates of peroxy radicals, which are ubiquitous intermediates in atmospheric oxidation. These species will be studied using many techniques: Cavity Ringdown Spectroscopy, Multiplexed Photoionization Mass Spectrometry, and Photoelectron-Photoion Coincidence Spectroscopy. The complementary approaches are designed to fully reveal how peroxy radicals evolve in atmospheric mechanisms and to characterize how their diverse chemical fates can lead to photochemical smog and secondary organic aerosol. Specific systems studied include the peroxy radicals derived from isoprene, the most important non-methane hydrocarbon emitted into the troposphere, and acetyl peroxy, whose reactions are believed to recycle oxidant in the tropics. The research will quantitatively address open questions about how unsaturated species are oxidized in the atmosphere and will lead to an understanding of organic aerosol formation and hydroxyl radical recycling mechanisms.
