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MS: Fachverband Massenspektrometrie
MS 6: Ion Storage Rings
MS 6.1: Invited Talk
Wednesday, March 16, 2011, 14:00–14:30, GÖR 229
Hot water in space — •Henrik Buhr — Weizmann Institute of Science, Rehovot, Israel — Max-Planck-Institut für Kernphysik, Heidelberg, Germany — Physikalisch-Technische Bundesanstalt, Braunschweig, Germany
Dissociative recombination (DR) of molecular ions with electrons plays an important role in many types of plasmas as destruction mechanism for ions and in the generation of neutral species, like water formation through DR of H3O+ in interstellar clouds. Information on the type and excitation of the DR products greatly helps understanding the chemistry in these environments and interpreting electro-magnetic spectra from telescope observations.
A new, energy- and position-sensitive detector recently implemented at the merged-beams facility at the TSR storage ring of the MPI für Kernphysik in Heidelberg yields impact positions and fragment identification on a single-event basis. This setup was used to study the DR of D3O+, i. e. the branching ratios into the various fragmentation channels for a wide range of collision energies as well as the kinetic energy releases and fragment excitations for each channel. The water formed in DR is highly excited with more than 3 eV, close to the dissociation limit into OD+D. This excitation might be the source of microwave emissions observed e. g. in cometary comae and laboratory water plasmas. Furthermore, the three-body fragmentation into OD+D+D shows a strong dependence of the correlation of fragment kinetic energies on the total kinetic energy release in the DR process.