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MPINP:
Quantendynamik - Abteilung Blaum
Abstract:
Ion-neutral collisions are pivotal for the gas-phase synthesis of complex molecules in the
interstellar medium. Accurate modeling of the astrochemical network relies on precise
laboratory data of reaction rate coefficients and their branching ratios. For the majority
of ion-neutral reactions, rate coefficients at astrophysical conditions are completely
unknown. To gain an experimental insight of ion-neutral, gas-phase chemistry under
interstellar conditions, two different experimental approaches are presented. One of
the most fundamental ions for interstellar chemistry is H3+ . This ion is assumed to
be thermalized in collisions with H2. However, recent astronomical observations of H2
and H3+ in diffuse interstellar clouds revealed a significant difference in their excitation
temperatures. In this work, 22 pole trap measurements, performed at the Max
Planck Institute for Nuclear Physics (MPIK) in Heidelberg, of the H3++ H2 reaction at
thermal equilibrium are presented and discussed. For future experiments on ion-atom
reactions, an injection beamline for the Cyrogenic Storage Ring (CSR) was developed
to perform merged-beams experiments on neutral ground-state atoms superimposed
with the cooled, stored ions in the CSR.
