Resonance absorption of N +2 first negative bands in irradiated air (U)

Abstract

A prescription is given for calculating the resonance absorption of N + 2 first negative (0, v) band radiation in strongly irradiated air. This prescription is based on a band model of resonance absorption reported previously. The rotational lines are assumed to be Lorentzian. The effects of overlapping lines and unequal emission and absorption line widths on the resonance absorption cross sections are included. Emission lines are broadened by pressure deactivation of the N + 2 B-state; absorption lines are broadened in resonant charge transfer collisions of N + 2 X-state ions with neutral N 2. N + 2 X-state ions are produced in cascades through the excited A-state. Vibrational populations of the X-state ions are nearly equal for v = 0, 1, 2. Most ions are formed with sufficient excitation energy (>1 eV) to activate ion-molecule reactions with N 2. Roughly 10% of N + 2−N 2 orbiting collisions result in ion-molecule reactions. The resonance absorption cross sections and N + 2 ion densities are related to dose rate, and an example is given of N + 2 first negative radiation from a uniformly dosed column of air.