Metastable Molecules in a Nitrogen Afterglow

The electronic metastable molecules in a nitrogen afterglow were sampled by detecting them in a thermalvelocity neutral beam extracted from the glow. Their variation as a function of time in the afterglow was compared with variations of N2 first positive and N2+ first negative emission from the glow. Variation of the former spectral feature may be interpreted as direct support for the recent suggestions (based on indirect evidence) that the process N2(A 3Σu+)+N→N2(X 1Σ)+N is fast. Variation of light from the ion suggests there is no direct connection between the concentration of metastable molecules and the production of excited ions. In an afterglow at 7 torr pressure, two different methods of determining the concentrations of metastable molecules yield very different results: 4×109 cm−3 as a lower limit and 2×1012 cm−3 as an upper limit. These values are discussed.