2019 年 62 巻 2 号 p. 86-92
The spectroscopic measurement of low-pressure microwave-discharged nitrogen plasma was conducted in the wavelength region of 550 to 1070 nm. Radiation from the N2 first positive band of the Δv=0 to Δv=+4 band series and nitrogen atomic lines were observed. The experimental spectrum was compared with the theoretical spectrum, showing the effect of the predissociation of N2 B 3Πg state through N2 A′5Σg+ state and triplet splitting for the transition of 3Π to the 3Σ state. They agreed very well with each other for the Δv=0 to Δv=+2 band series, which consisted of the lower vibrational levels of Δv′=0 to 7, but did not agree well for the higher vibrational levels of Δv′=8 to 12 in the Δv=+3 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 3Πg state was estimated to be a non-Boltzmann distribution at the higher vibrational levels. In addition, the theoretical vibrational population distribution in the B 3Πg 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.
