SECONDARY IONS PRODUCED FROM GASEOUS AND FROZEN H2O UNDER ENERGETIC (MEV AMU) AR ION IMPACT/

Mass/charge spectra of secondary ions produced under energetic (simila r to MeV/amu) Ar ion impact on gaseous and frozen H2O targets are meas ured using a magnet-type mass spectrometer. The ion spectra are found to be quite different between these target phases. Multiply charged O- i+ ions with charge states i=2-6, as well as fragmented H+, O+, and OH + ions, are clearly observed in the gas target, whereas the production of multiply charged ions is strongly suppressed in the frozen target. The most intense ion species is the parent H2O+ ion in the gas target ; the H3O+ ion in the frozen target. The most outstanding feature in t he frozen target is that the production of cluster ions of the type (H 2OH+ (n=1-31), and their intensities, decreasing as the cluster size n increases, show anomalies between n=4 and n=5 and also around n=20, 2 1, and 22. Negatively charged cluster ions with formula (H2OO- and (H2 O)(n)OH- are also efficiently produced in the frozen target.