a) TPD curve, with a heating rate of 2 K min^-1, of ~800 ML of pure CH₃NC deposited on polycrystalline gold at 90 K. The beginning of the desorption has been magnified by a factor of 10. b) Infrared spectra in the region of the NC stretching vibration, during the warming up of the ice. c) Plot of the logarithm of the desorption flux as a function of the inverse of the temperature. Lines are linear fits of the plot.