Abstract: A new scheme is proposed for the spectroscopic experiment of diatomic molecule based on nitrogen molecules （N2） in the college course of modern physics experiment. The emission spectrum of the second positive band of N2 can be recorded with a normal grating spectrometer equipped with a photomuhiplier as detector and a glow discharge of low-pressure N2 as the spectral source. According to the basic theory of electronic-vibrational spectrum of diatomic molecule, the harmonic frequencies and anharmonic parameters in the upper and lower electronic states of N2 can be derived from the observed spectrum.

Key words: nitrogen molecule, spectrum of diatomic molecule, modern physics experiment