Example of synthetic generated spectrum (#21), normalised by its mean absorbance value. The colours represent the different molecular contributions. This spectrum represents a layered mixture of H₂O, CO, CH₃OH, NH₃, CO₂, and CH₄, in decreasing order molecular fraction, all of them at a temperature of 11.7 K. The pure ice spectra used to construct this curve come from different experiments from LIDA, OCdb and Univap (see Table D.1), at different temperatures close to 11.7 K (see Section 2.3.4 for more details).