Ion irradiation of astrophysical ices

We report recent experimental studies on the physical—chemical effects induced by fast ions colliding with frozen gases (CO. CH3OH, CH4, CO2) and mixtures with water simulating icy targets in space (frosts on external planets and satellites. comets and interstellar ices). We have studied, by lR spectroscopy, the formation of new molecules. the alteration of band profile. the spectral changes of the original compounds and the formation of an organic refractory residue left over after ion irradiation. In particular; we present here the results of the measurements of the CO CO2 ratio resulting from the irradiation of several ice mixtures.