Hannover 2013 – scientific programme

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MO: Fachverband Molekülphysik

MO 18: Experimental Techniques

MO 18.7: Talk

Wednesday, March 20, 2013, 15:30–15:45, F 102

Optimized Cooling and Transmission of Pulsed High-Density Molecular Beams — •Wolfgang Christen and Bo-Gaun Chen — Humboldt-Universität zu Berlin, Institut für Chemie, Brook-Taylor-Straße 2, 12489 Berlin, http://clusterlab.de

Pulsed jet sources facilitate beam parameters that are hardly accessible with a continuous expansion. Most notably, they provide a means to substantially increased source densities, allowing for the convenient and reliable generation of supersonic beams including liquid and supercritical stagnation conditions. However, obtaining meaningful values for the mean cluster size, kinetic energy, and temperature at high beam densities also requires a collision-free beam propagation. At increased source densities this is a non-trivial and frequently neglected issue.

We demonstrate the substantial influence of background gas pressure and beam-skimmer interactions on the minimum attainable beam temperature. The thorough analysis of beam properties and the correspondingly optimised choice of expansion parameters result in much colder beams, at the same conditions of source pressure and temperature, allowing to reduce the beam temperature by more than one order of magnitude.