Interaction Of Heavy Ions With Ices In Astronmical Environment

This thesis concerns irradiation of ices composed of simple molecules (H2O, CO, CO2, NH3) with heavy ion beams at GANIL. These ices exist in several astrophysical environments such as comets, surfaces of satellites of giant planet, and dense molecular clouds. Irradiation in the laboratory allows simulating the effects of cosmic rays with high energy ion beams, and those of solar wind with low energy beams. The analysis is performed by Fourier transformed Infrared absorption spectroscopy, which allows detecting molecules created during ion irradiation. The evolution of the ices, characterized by destruction cross sections, formation cross sections and sputtering yields was studied as a function of electronic stopping power for some of the most abundant simple molecules in space. Furthermore, Implantation experiments were performed in order to study chemistry induced by the projectile ions and formation of molecules such as CO2and SO2. The formation rates were compared to the corresponding observations of abundance of those molecules and the Jovian moon Europa. After irradiation of the mixture CO2+NH3several new species such as CO, OCN-et [HCOO-][NH4+] were observed. This indicates that complex organic molecules can possibly be formed by irradiation of ices in space.