Spatially Resolved N₂(A³Σ_u⁺, ν = 0) Decay Studies in the Pulsed Direct-Current Nitrogen Discharge using the Laser-Induced-Fluorescence Technique

We focus on the investigation of the spatial distribution and temporal evolution of N₂ (A³Σ_u⁺, ν = 0) in a very early afterglow of a pulsed dc nitrogen discharge. The results indicate that a fast quenching process of N₂ (A³Σ_u⁺, ν = 0) exists in the very early afterglow. We study the dependence of this fast quenching process on the discharge pressure 20–40 torr. It seems that this fast quenching behavior of N₂ (A³Σ_u⁺, ν = 0) found in our experiment can be ascribed to the combined action of pooling reaction and collisions with N atoms through N₂ (A³Σ_u⁺)+N₂ (A³Σ_u⁺) → N*₂+N₂(N*₂=N₂(B³Π_g, C³Π_u, C'³Π_u, C''⁵Π_u)) and N₂(A³Σ_u⁺)+N(⁴S)→N(²P)+N₂, respectively. Meanwhile, the decay studies of N₂(A³Σ_u⁺, ν = 0) near the anode and cathode infer that the production of N(⁴S) atoms does not distribute uniformly along the axis of the discharge gap at relatively low pressure, and this effect becomes gradually inconspicuous with the increasing discharge pressure.