A laboratory study of water ice erosion by low-energy ions

Water ice covers the surface of various objects in the outer Solar system. Within the heliopause, surface ice is constantly bombarded and sputtered by energetic particles from the solar wind and magnetospheres. We report a laboratory investigation of the sputtering yield of water ice when irradiated at 10 K by 4 keV singly (13C+, N+, O+, Ar+) and doubly charged ions (13C2+, N2+, O2+). The experimental values for the sputtering yields are in good agreement with the prediction of a theoretical model. There is no significant difference in the yield for singly and doubly charged ions. Using these yields, we estimate the rate of water ice erosion in the outer Solar system objects due to solar wind sputtering. Temperature-programmed desorption of the ice after irradiation with 13C+ and 13C2+ demonstrated the formation of 13CO and 13CO2, with 13CO being the dominant formed species.Comment: 10 pages, 7 figures, 3 tables, accepted for publication at MNRA

Development of a novel mass spectrometric technique for studying DNA damage

Abstract An experimental system, based upon UV and IR laser desorption, has been constructed to enable the production and characterization of neutral biomolecular targets. These targets are to be used for interaction experiments investigating radiation-induced damage to DNA. The viability of the laser-desorption techniques of MALDI (matrix-assisted laser-desorption ionization), SALDI (surface-assisted laser-desorption ionization) and DIOS (desorption/ionization on silicon), for production of these gas targets is discussed in the present paper. Fluorescent dye tagging and LIF (laser-induced fluorescence) imaging has been used to characterize the biomolecular plumes, revealing their spatial density profiles and temporal evolution

Fragmentation of acetonitrile in collisions with H– and O– ions

Relative cross sections for the production of negatively charged fragments have been determined as a function of ion impact energy in low-energy (0.5 - 5.5 keV) collisions of H– and O– with acetonitrile molecules. The most abundantly produced negative ions from fragmentation by H– and O– impact are CH3CN–, CH2CN– and CN–. Notably, the parent negative ion CH3CN– is produced abundantly

Fragmentation of acetonitrile in collisions with H– and O– ions

Relative cross sections for the production of negatively charged fragments have been determined as a function of ion impact energy in low-energy (0.5 - 5.5 keV) collisions of H– and O– with acetonitrile molecules. The most abundantly produced negative ions from fragmentation by H– and O– impact are CH3CN–, CH2CN– and CN–. Notably, the parent negative ion CH3CN– is produced abundantly