Cluster emission and chemical reactions in oxygen and nitrogen ices induced by fast heavy‐ion impact

Abstract:

Two ices, O2 and a mixture of O2 and N2, are bombarded by 252Cf fission fragments (FF) (∼65 MeV at target surface); the emitted positive and negative secondary ions are analyzed by time‐of‐flight mass spectrometry (TOF–SIMS). These studies shall enlighten sputtering from planetary and interstellar ices. Three temperature regions in the 28–42‐K range are analyzed: (1) before N2 sublimation, in which hybrid chemical species are formed, (2) before O2 sublimation, in which the TOF mass spectrum is dominated by low‐mass (O2)p cluster ions and (3) after O2 sublimation, in which (N2)p or (O2)p cluster ions are practically inexistent. In the first region, four hybrid ion series are observed: NOn−1+, N2On−2±, and N4On−4−. In the second region, two positive and negative ion series are identified: (O2)pO± and (O2)pO2±. Their yield distributions are fitted by the sum of two decreasing exponentials, whose decay …

Año de publicación:

2008

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