Abstract: Mehane (CH4) and nitrogen (N2) are two main gas components of many terrestrial stars, and HCN, CN and C2H2 et al are the main products from the mixture of these two gases. The formation process of the main products is simulated by CH4/N2 discharge plasma, and the relative concentrations of HCN and C2H2 are obtained by measuring the absorption spectra based on mid-infrared wavelength modulation absorption spectroscopy. The results show that the relative concentrations of HCN and C2H2 depend on the ratio of C/N in the mixed gases, and excess N2 is beneficial to the formation of HCN, while excess CH4 is beneficial to the formation of C2H2. Further study shows that the main formation pathway of HCN is CH3+N! HCN+H2. In addition, C2H2 generated by CH4/N2 glow discharge may further combine with N2 to form HCN.

Key words: spectroscopy, plasma spectrum, HCN molecules, absorption spectroscopy, wavelength modulation spectroscopy