Organic ion species sputtered from contaminated water ice by 1.5 MeV N2+ ions

Electronic sputtering of organic species being mixed to water ice by residual-gas condensation is analyzed by secondary ion time-of-flight mass spectrometry. The ice samples were prepared at 15 K by deposition from a H2O gas-flow and irradiated by 1.5 MeV N2+ ions while the temperature was raised up to 216 K. Desorption ion yields of positive H2O specific ions as of some organic ion species are measured as a function of temperature. Remarkably high desorption yield variations, mainly of the CnHm ions, were observed during the enrichment of organics hiding the emission of (H2O)nH3O+ cluster ions.