[en] A new infrared radiation has been detected in the night sky, which is far more intense than the ordinary persistent aurora giving the green line at 5577 A. Measured with a photocell and filters, the wave length of the new radiation is 10,440 ± 25 A.
This night-sky radiation is identified with the (0, 0) band of the first positive group B3∏ → A3Σ of N2. The absence of other N2 bands suggests that emission of the (0, 0) band involves conversion of the energy of dissociation D(N2) into excitation in a three-body collision:
N + N + N2 → N2 + N2exc .
Since D(N2) is a little larger than the excitation energy of B3∏, ν' ≈ 0, but smaller than B3∏, υ' = 1, only the bands arising from B3∏, υ' = 0, would be excited; and of the latter, only (0, 0) is observable. This mechanism implies the presence of a large number of nitrogen atoms in the high atmosphere. It can be effective only with the value 7.38v. of D(N2) advocated by Herzberg and Sponer.
