Vibrational relaxation of N2(C, v) state in N2 pulsed rf discharge: electron impact and pooling reactions Original Research Article

The decay of Δv = −2 band sequence of N2 Second Positive emission system has been investigated in a N2 rf pulsed 500 Hz post discharge in the pressure range 0.1–3 Torr. The intensity of each band head of the sequence has been used to infer the N2(C, v′ = 0–4) relative vibrational distribution. The shape of the distribution varies significantly with the post discharge time and the pressure. A population inversion in the levels 0–1 and 2–3 characterizes the distributions measured at post discharge times higher than 100 μs. The distributions at the various post discharge times have been fitted by a model which takes into account three processes for the (C, v′) excitation: the electron impact from (X, v) states by fast electrons (a), from (A, w) state by slow electrons (b), and the pooling reaction N2(A, w) + N2(A, w′) (c). In the discharge the excitation is predominantly given by process (a). At 1 ms in the post discharge the electronic process (b) still survives, and, together with process (c), provides excitation to C state.