X-ray photodesorption intensities divided by the photon flux (in A s photon⁻¹) at 420 eV of desorbing species from pure acetonitrile ices. The mass channels monitored during the experiments are indicated on the X-axis. The attribution of these mass channels to desorbing neutral species is discussed in the text. The different colors are associated with a natural (green) or an isotopic (orange) ice, irradiated at 15 K. The signals were obtained for a fluence <2 × 10¹⁶ photons cm⁻², and they are not corrected for any possible fragmentation of desorbing species in the ionization stage of our QMS.