Berlin 2005 – scientific programme

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MO: Molekülphysik

MO 22: Poster I

MO 22.6: Poster

Saturday, March 5, 2005, 10:30–12:30, Poster HU

EXPERIMENTAL STUDY OF COLD ATOM-MOLECULE COLLISIONS IN A MAGNETIC TRAP — •Sophie Schlunk¹, Allard Mosk², Wieland Schöllkopf¹ und Gerard Meijer¹ — ¹Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany — ²University of Twente, Enschede, The Netherlands

Cooling and trapping of molecules is difficult mainly because laser cooling, in contrast to atoms, has not been applicable to molecules. In addition, cooling a molecular gas by forced evaporation or by sympathetic cooling with atoms has not yet been demonstrated at sub-millikelvin temperatures. Its efficacy depends on the rates of elastic and inelastic (trap-loss) collisions. For molecule-molecule as well as for most atom-molecule collisions the corresponding low temperature cross sections cannot be predicted by theory because of uncertainties in the best-known interaction potentials. We plan to experimentally study cold atom-molecule collisions. A large elastic-to-inelastic collision-rate ratio is prerequisite to sympathetically cool molecules with atoms in a 2-species trap.

We have cooled Rb-atoms in a standard magneto-optical trap (MOT) loaded from a Zeeman-slower. After transfer to and adiabatic compression in a magnetic trap a density on the order of 10¹¹ atoms/cm³ and a temperature of about 1 mK is expected. We plan first to study collisions between Rb-atoms and molecules at well defined and variable relative velocities by colliding a thermal or Stark-decelerated beam of heteronuclear molecules (e.g. NO, CO^∗, or ND₃) with the cold Rb-atom target. Eventually, we plan to explore sympathetic cooling of heteronuclear polar molecules with Rb-atoms confined simultaneously in 2-species trap.