Quantum Calculation of the Vibrational Excitation of Nitrogen Molecules by Fast Ions: Can It Contribute to STEVE Formation?

Abstract

AbstractThe vibrational‐translational (VT) excitation of nitrogen molecules led by collisions with fast ions in subauroral ion drifts (SAID) has been conceived as a potential underlying mechanism contributing to the formation of the Strong Thermal Emission Velocity Enhancement (STEVE) phenomenon (Harding et al., 2020, https://doi.org/10.1029/2020gl087102). In this study, we perform quantum calculations of the VT excitation rates of N2 led by fast‐drifting ions, and evaluate the resulting vibrational distribution of N2 with ionospheric/thermospheric parameters expected under intense SAID condition. We conclude that, while the VT energy transfer led by SAID plays a distinguishable role in the vibrational excitation of N2, it is incapable of populating the high vibrational levels to the required concentration (Harding et al., 2020, https://doi.org/10.1029/2020gl087102) to produce adequate nitric oxide density, and in turn the nitrogen‐dioxide continuum intensity, to account for the STEVE brightness.