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Abstract

An important participant in interstellar chemistry is the H+3 molecular ion. Its concentration depends on the rate coefficient of dissociative recombination with electrons at low temperatures. Experiments aiming at a determination of this rate coefficient scatter by several orders of magnitude. This might by attributed to vibrational or rotational excitations of the H+3 molecular ions. In particular previous storage ring experiments revealed long lifetimes of certain rotational excitations. Hence a source for rotationally cold H+3 molecular ions was installed at the Max-Planck-Institut fur Kernphysik in Heidelberg. The setup is based on a cryogenic 22-pole radiofrequency ion trap which allows collisional cooling of the H+3 molecular ions by the use of helium buffergas. The molecular ions can be extracted from the trap and transferred to the storage ring (TSR) for recombination experiments. First results suggest that by the use of this setup a spectrum of the dissociative recombination of cold H+3 molecular ions could be measured. Moreover the setup can be used to probe gas phase chemical reactions at low temperatures. The formation of deuterium cluster ions at 13K was studied and rate coefficients for association and dissociation reactions of these clusters ions could be extracted.