Laboratory Studies of Mesospheric Nightglow Mechanisms

Throughout the night, various chemical reactions, energy transfer, and other excitation processes in Earth’s upper atmosphere contribute to a weak light emission known as the nightglow. Space- and ground-based observations, atmospheric models, theoretical calculations, and laboratory investigations of the underlying fundamental processes are needed to advance the state of knowledge about this relatively less well understood atmospheric region in which space meets the Earth’s atmosphere.
Reliable interpretation of nightglow emissions requires understanding how the emitting layer is generated and detailed knowledge of the relevant photochemical production mechanisms at the atomic and molecular level. The energy transfer processes and reactions that deactivate the emitting species are also just as important because the observed emission intensity reflects the competition between the production and loss pathways.
Our laboratory studies investigate the pathways involving excited electronic states that play an important role in the nightglow. Specific examples include the recombination of O atoms to generate various excited states of molecular oxygen and the coupling of the OH Meinel band emission with other nightglow emissions, mediated by multi-quantum OH(v) vibrational relaxation in collisions with O atoms. We will report on our recent experimental findings and their implications for mesospheric nightglow emissions.
This research was supported by the NASA Heliophysics (80NSSC23K0694) and NSF Aeronomy Programs (AGS-2113888, AGS-2009960).