The Isotope Effect to the IR Emissions of CO and CO2 produced by 15 keV H3+ irradiation of H2O (D2O)/ CO, CO2, CH4 or CH3OH icy mixtures.

Simulation of ices covered astronomical surfaces irradiated by 15 keV H3+. We have measured the particle irradiation of interstellar icy materials such as H2O mixed with CH4, CO, CO2, and CH3OH resulting the synthesis of CO and CO2. The technique used to identify and quantify the synthesized species has been infrared spectroscopy. Irradiation of pure water ice produces OH and no CO and CO2. Irradiation of pure CH4 causes the formation of CH4 and C2H6, but no CO and CO21. On the other hand, irradiation of pure CH3OH ice produces CO and CO22. Tow IR emissions of CO2 (2339 cm-1) and CO (2136 cm-1) produced by ion irradiation of all icy mixtures are compared with H2O abundance. The experimental results are discussed with a view to the relevance they could have in planetary environments such as icy moons in the external solar system.