Heidelberg 2015 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 11: Posters 2: Novelties in Molecular Physics

MO 11.12: Poster

Dienstag, 24. März 2015, 17:00–19:00, C/Foyer

A versatile neutral-ion collision setup for the CSR — •Florian Grussie, Manfred Grieser, Aodh P. O’Connor, and Holger Kreckel — Max-Planck-Institut für Kernphysik, Heidelberg

Ion-neutral reactions are pre-eminent processes in the chemical network of interstellar clouds. With typical cloud temperatures ranging from 10 to 100 K, neutral-neutral reactions tend to be energetically quenched. Anion-cation reactions, although often barrier-less, are limited due to the relatively low abundance of anions in interstellar clouds. With approximately 180 cosmic molecules detected to date, two-body neutral-ion collisions are prevalent in the formation of complex molecules. Despite their importance, most ion-neutral reactions have no experimental thermal rate coefficient data at astrophysically relevant conditions.
To study these processes, we are currently developing an apparatus to merge cooled stored ions (∼ 10 K) with a well-defined neutral atomic beam. To this end, a negative ion beam with a kinetic energy of up to 300 keV, is crossed with a continuous wave high-power (2 kW) diode laser, operating at 808 nm. Neutral particles are created by photodetachment and merged with stored ions in a straight section of the Cryogenic Storage Ring (CSR) at a tuneable center of mass collision energy. The CSR, located at the Max Planck Institute for Nuclear Physics in Heidelberg, provides a cold environment (∼ 10K) with extremely low residual gas pressure. Measurement of the particle fluxes, beam overlap and the production rate of daughter products enable determination of absolute reaction rate coefficients.