Ion desorption by high energy irradiation of ices and Astrophysical implications

Abstract

We have studied by time of flight mass spectrometry the ion desorption from icy films stimulated by the irradiation of MeV/amu Kr ions. We have determined the mass of the desorbed species, and detected clusters of the form H(H₂O)_n+, O(H₂O)_n− and OH(H₂O)_n−, with n higher than 20. We have measured the variation of the desorption yields with the energy of the primary beam, for both the positively and negatively charged ions. The production of ions with high masses induced by the cosmic ray bombardment of icy grains may play an important role in cosmic chemistry.