Keywords: 
• 第二正带系 /
• 发射光谱 /
• 跃迁概率 /
• 电晕放电

Abstract: The optical emission spectrum of the second positive system of N2（CUHu -BaHg） is analyzed and calculated based on the energy structure of the triplet systems of nitrogen radicals. Some key parameters of the equation for the radiative transition intensity are evaluated theoretically, including the potentials of the upper and lower states obtained from diagonalizing their Hamiltonian matrices, the electronic transition moments calculated by using r-centroid approximation, and the Einstein coefficients of different vib-rotational levels. For comparing with the theoretical spectra, we achieve the measured results from corona discharge experiments of N2 and Ar. By fitting the measured spectral intensities and the calculated ones, the vibrational and the rotational temperatures are determined approximately to be 4300 K and 800 K. The results also demonstrate that with the reduction of nitrogen concentration, the intensity of N2 radiative state first increases and then decreases due to Penning excitation from argon metastable states. The experimental results verify the correctness of the theoretical calculations on the second positive system.