Sodium-Atom Excitation in Nitrogen Afterglows

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Abstract
The addition of Na metal vapor to nitrogen discharge afterglows in a fast flow system produced strong Naatomic excitation and ionization. Spectroscopic techniques were used to determine the relative populations of several Na atomic levels for Na excitation in the nitrogen pink and Lewis–Rayleigh afterglows. Three sets of Na f values were used. For nitrogen afterglow pressures of 2–10 torr, the populations of the Na 4 2 P and several higher atomic levels appear related by a Maxwell–Boltzmann distribution. MeasuredNa excitation temperatures were 4500 ± 300°K in the N2 pink and 4000 ± 200°K in the Lewis–Rayleigh afterglows. A double‐probe measurement of the electron temperature in the pink afterglow yielded a value of 5000°K. Comparison with earlier work indicates that the Na excitation temperature corresponds to the N 2 (X 1 Σ) vibrational temperature. These results support the hypothesis that the Naatomic excitation and ionization are produced by energy transfer between the N 2 (X 1 Σ) vibrational states and the Na‐atom electronic states.