Swift heavy ions irradiation of water ice at different temperatures: hydrogen peroxide and ozone synthesis and sputtering yield

Abstract

Water ices at 15 and 144 K were bombarded by swift heavy ions, 45.8 MeV 58Ni11 + and 606 MeV 64Zn26 +, to measure the induced chemical and physical effects. The column densities of water and the synthesized species, hydrogen peroxide (H2O2) and ozone (O3), were monitored via infrared spectroscopy. The formation and destruction cross-sections of precursor and products were determined and compared with literature. The H2O2 formation and destruction cross-sections reveal a linear dependence with electronic stopping power, σ Se. The sputtering yield (Y0) shows a power law with electronic energy lost, $Y0\propto S\mathrm{e}2$, and an exponential increase with the sample temperature. The findings indicate that the radiolysis rate of water ice is higher at low temperatures while the desorption yield increases at higher temperatures. A large amount of water ice is located in the grain mantles of the circumstellar envelopes and the interstellar medium regions, which are exposed to galactic cosmic rays (GCRs). The synthesis of H2O2 and O3 molecules as a function of absorbed doses of GCR irradiation and their irradiation time is analysed in detail. Besides, the extrapolation of the sputtering yield rates, as a function of time and temperature, for astrophysical conditions can contribute to a better understanding of non-thermal sputtering of water ices.