Production Pathways and Yields of Excited O2 Important for Mesospheric Nightglow

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This award would support the laboratory studies of the reactions that lead to molecular oxygen electronically excited states that are observed in the Earth's mesospheric and lower thermosphere (MLT) nightglow (70 to 110 km). The award would investigate the role of collisional relaxation within the dominant energy flow pathways and would measure the O2 excited-state yields resulting from the process of termolecular association of oxygen atoms. These measurements would provide a quantitative understanding necessary to support the reliable modeling of the atmosphere MLT airglow emissions removing the significant gaps and reducing uncertainties that currently exist in the understanding of these processes. Laser-based laboratory methodologies would be used to investigate MLT nightglow emissions that have recently led to major breakthroughs in the understanding of these nightglow phenomena. Finally, the proposed research will contribute to the development of research experiences for undergraduate students while also providing training for one or more postdoctoral fellows.These laboratory studies will provide insight at the atomic and molecular level into the underlying production mechanisms, energy flow pathways, and yields of the excited O2 states produced following termolecular O-atom association. These investigations will also supply basic physical measurements currently needed to interpret and model important O-atom processes that generate electronically excited O2 in the Earth’s mesosphere. These measurements will quantify the O2 airglow mechanisms allowing the subsequent probe of atmospheric composition and dynamics by remote sensing. Application of basic chemistry and physics to the study of collisional and molecular energy transfer processes on a fundamental level is also critical for understanding combustion, astrophysical environments, as well as the operation of lasers, especially high-power chemical lasers.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.