Superposition of FTIR spectra of different residues compared to the spectrum of an UCAMM. From top to bottom: poly-HCN before and after annealing to 600 K (Bonnet et al. 2015); spectrum of a UCAMM (Dartois et al. 2013); spectrum of residue “d” of this work, post-annealed to 600 K (in red), spectra of residues “a” to “d” produced in this work after irradiation and annealing to 300 K (in blue); spectrum of pure HCN ice after irradiation with 0.8 MeV protons (Gerakines et al. 2004).