NH₃−¹³CO (and H₂O) co-deposition experiments. The mass channels used for H₂O, NH₃, and ¹³CO are 18 amu, 17 amu, and 29 amu, respectively, also accounting for fragments of mass = 17 amu (for H₂O) and 16 amu (for NH₃). All experiments were performed on a gold substrate. The TPDs have a ramp of 0.2 K s⁻¹. Lines of the same colour belong to the same set of experiments. The dash-dot vertical line at 155 K corresponds to the temperature of the phase change of water from amorphous to crystalline.