Laboratory Studies of O(1D) Processes Important in the Upper Atmosphere

Sri International, Menlo Park CA

Investigators

Abstract

The investigators will conduct a series of experiments on atmospherically important processes involving oxygen atoms in the singlet D state [O(1D)]. First, they will measure the rate coefficient for the collisional removal of O(1D) by oxygen atoms in the triple D state [O(3D)] and its temperature dependence in the range 300 to 1000 K. Recent laboratory studies at room temperature have indicated that relaxation by oxygen atoms is the most significant process controlling the intensity of the 630 nm red line emission at altitudes 200-300 km. The study will yield the first set of laboratory measurements at the relevant high temperatures. The investigators will also investigate the temperature dependence of other reaction rates important for understanding atmospheric oxygen emissions. These laboratory experiments are essential for improving the currently incomplete understanding of ionospheric red-line emission, allowing for better modeling and quantification of molecular oxygen Atmospheric Band emissions, and elucidating the role of oxygen atom energy transfer in the altitude range 120-400 km. Also, knowledge of the rate coefficient for the collisional removal of O(1D) by O(3P) allows the correct interpretation and analysis of the O(1D) emissions. These results will enhance the scientific return of ionospheric heating experiments by enabling a correct interpretation and quantification of the 630-nm red line emission. The rate coefficients to be measured are relevant to both calm and perturbed atmospheric conditions. This work should also help improve understanding of satellite drag and the interpretation of results from incoherent scatter radar measurements. Energy balance in the upper atmosphere is key to modeling the Earth as a system. Application of basic chemistry and physics to the study of collisional energy transfer processes on a fundamental level is also critical for understanding the operation of lasers, especially high-power chemical lasers. Finally, the study will contribute to training, mentoring, and research experiences of postdoctoral fellows and summer undergraduate students.