Densities of active species in N₂ and N₂–H₂ RF pink afterglow

The transverse distribution of N₂ radiative states has been analyzed in the early afterglow of RF N₂ flowing discharge with the introduction of a few H₂ molecules (10⁻⁵–10⁻³) in the discharge. The transverse distributions of N₂, 1st (580 nm), 2nd pos (316 nm) and N₂⁺,1st neg (391.4 nm) band intensities have a sharp profile in pure N₂. As more H₂ was introduced into N₂, a sharper profile for the N₂⁺,1st neg was observed, and inversely a broader profile for the N₂, 1st pos. With the introduction of H₂ into N₂ the early afterglow was changed from a sharp pink to a broad late afterglow where the N + N recombination is the dominant process. After NO titration of N-atom density in pure N₂ late afterglow, the variation of N-atom and N₂(A) density in the N₂–H₂ early afterglow is deduced. The N₂(X, v > 13) density is also estimated. (paper)