Mass spectrum of an irradiated gas mixture of 95% H₂ + 5% CH₄ (Gray). Fragmentation patterns (FP) of the two-carbon atoms (A.1a) and three-carbon atoms (A.1b) compounds (Pink for the alkanes, orange for the alkenes, green for the alkynes). Each FP is normalized to the intensity of the experimental spectrum at the m/z value corresponding to the most intense peak of the FP. 95% uncertainty bars are displayed in black.