W-band spectrum of a CH₄ and N₂ plasma at a total pressure of 32.4 × 10⁻³ mbar and a RF power of 20 W. The total integration time was 40 min per W sub-band. The observations were performed in frequency switching mode. The strongest feature corresponds to HCN. The features above the noise level correspond to HC₃N in the ground state and in the ν₇ and 2ν₇ modes. Many weak features correspond to CH₃CN. The frequency domain 82–91 GHz is observed in both WL and WM sub-bands, and shows a better S/N. The same happens with the range 95.5–101 GHz that is observed in both WM and WH sub-bands.