Quenching of the N₂Vegard-Kaplan System in aurora

New measurements by ground-based spectroscopy of the N2 Vegard-Kaplan system have given values for the υ′ progression intensities from υ′ = 0 to υ′ = 3 and upper limits to the values from υ′ = 4 to υ′ = 6. These are combined with other recent measurements of the N2 1P system and theoretical estimates of direct electron impact excitation to the A³Σ state to yield estimates of the rate coefficient for quenching of the A³Σ state by O and the variation of this coefficient with υ′. For the υ′ = 0 level a rate coefficient of 7.5 ± 5.0 × 10−11 cm³ s−1 is found to be consistent with reasonable assumptions as to atmospheric composition and auroral luminosity profile. It is concluded that this coefficient must double in value in the range 2 < υ′ < 5.