TPD curves of methylamine giving the desorption rates (ML s⁻¹) of the mass (m∕z = 31) as a function of the temperature of the surface (K). The thin red line indicates 1 ML of CH₃ NH₂ deposited on graphite HOPG substrate at 40 K; the thick red line represents 0.30 ML of CH₃ NH₂ deposited on the np-ASW ice surface held at 40 K; the thick magenta line indicates 0.35 ML of CH₃ NH₂ deposited on the np-ASW ice surface at 40 K; and the blue dashed line represents TPD curve of H₂O (m∕z = 18) for 10 ML of the np-ASW ice film prepared at 110 K on the HOPG surface and cooled down to 40 K (scaled by 0.001).