Desorption curves for TPD experiments involving NH₄⁺HCOO⁻and H₂O ice: (a) pure NH₄⁺HCOO⁻ and (b) a film of 15 ML of H₂O deposited bellow 3.5 ML of NH₄⁺HCOO⁻. The heating rate is 0.2 K s⁻¹. In panel b, the water desorption peak is scaled to align with the proportion of the salt peak. The deposition temperature and the deposition dose for each component in the mixture are listed in each experiment.