The spectroscopic measurement of low-pressure microwave-discharged nitrogen plasma was conducted in the wavelength region of 550 to 1070 nm. Radiation from the N 2 first positive band of the Áv ¼ 0 to Áv ¼ þ4 band series and nitrogen atomic lines were observed. The experimental spectrum was compared with the theoretical spectrum, showing the effect of the predissociation of N 2 B 3 ¬ g state through N 2 A 0 5 g + state and triplet splitting for the transition of 3 ¬ to the 3 state. They agreed

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... ery well with each other for the Áv ¼ 0 to Áv ¼ þ2 band series, which consisted of the lower vibrational levels of v 0 ¼ 0 to 7, but did not agree well for the higher vibrational levels of v 0 ¼ 8 to 12 in the Áv ¼ þ3 and +4 band series. By comparing the band head intensity of the experimental and theoretical spectra, the experimental vibrational population on each vibrational level for the B 3 ¬ g state was estimated to be a non-Boltzmann distribution at the higher vibrational levels. In addition, the theoretical vibrational population distribution in the B 3 ¬ g state was calculated using a master equation, and then agreement between the experimental spectrum and the theoretical spectrum with the non-Boltzmann distribution obtained from the master equation was improved. Nomenclature Aðv 0 ; v 00 Þ: sum of radiative transition probability from vibrational level v 0 in B 3 Å g state to all vibrational levels in A 3 AE u þ state Kðc; v 0 Þ: recombination rate coefficient to vibrational level of v 0 Kðv 0 ; cÞ: dissociation rate coefficient from vibrational level of v 0 Kðv; v 0 Þ: transition rate coefficient from an initial level v in B 3 Å g state to final level v 0 J max : maximum rotational quantum number n M : population of third body n S : population in 4 S°state of nitrogen atom n v 0 : population of vibrational level v 0 T r : rotational temperature T v : vibrational temperature v 0 : vibrational level in B 3 Å g state v 00 : vibrational level in A 3 AE u þ state Áv: v 0 À v 00 V max : maximum vibrational quantum number ! D : surprisal parameter for dissociation