The vibrational distribution of N 2 + in the terrestrial ionosphere

Abstract

The densities and vibrational distributions of N2+ in the X²Σg+, A²Πu, and B²Σu+ states in the daytime terrestrial ionosphere are computed for both low and high solar activity. Altitude profiles of the relative populations of the vibrational levels of N2+X²Σg+ are presented. The fraction of vibrationally excited N2+ varies from 5% at 100 km to 50% at 450 km. Several models are examined in which loss of N2+(v) is enhanced for v > 0 and in which various assumptions are made about the vibrational distributions produced in charge transfer reactions. The N2+ densities are significantly reduced if N2+(v) reacts with O at rates which are near gas-kinetic. Vibrational distributions of the A²Πu and B²Σu+ states are also presented, as well as volume emission rates and integrated overhead intensities of the major bands of the Meinel and first negative systems.