Top: experimental CRD spectrum of the sampled gas collected after exposure to a shock wave (initial mixture: C₆₀ = 139 μmol, Ar = 0.229 mol, H₂ = 0.054 mol) with a reflected shock gas temperature T_g of 2996 K. Bottom: simulated spectrum of methane CH₄ and ethylene C₂H₄ from the WKMC (Campargue et al. 2012) and ethylene linelists (Lyulin et al. 2014). The presence of residual water vapor is accounted for with the help of the Hitran 2012 database (Rothman et al. 2013). During the shock, a ratio of H/H₂ ~ 0.068 is achieved.