Frankfurt 2006 – scientific programme
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MO: Molekülphysik
MO 54: Cold Molecules II
MO 54.5: Talk
Thursday, March 16, 2006, 15:00–15:15, H10
Stark deceleration and trapping of OH radicals — •Steven Hoekstra, Joop J. Gilijamse, Sebastiaan Y.T. van de Meerakker, and Gerard Meijer — Fritz-Haber-Institut der Max-Planck-Gesellschaft,Faradayweg 4-6, 14195, Berlin
Over the last years our group has been developing methods to get improved control over the absolute velocity and the velocity spread of molecules in a molecular beam. With the Stark decelerator, a part of a molecular beam can be selected and transferred to any arbitrary velocity, producing bunches of state-selected molecules with longitudinal temperatures as low as a few mK.
We will report on the electrostatic trapping of ground state OH radicals. Typically 105 groundstate OH radicals are trapped for times up to 1.5 seconds at a temperature in the 50-500 mK range [PRL 94 23004 (2005)]. The long interaction time offered by the trap can be exploited to measure the radiative lifetime of long-lived excited states of a molecule [PRL 95 013003(2005)]. Furthermore, we have optimized the trap loading by using evolutionary strategies, resulting in an increase of the number of trapped molecules by 40%.
Recently we have performed the first inelastic scattering experiments using a Stark decelerated beam of polar molecules. Groundstate OH radicals are decelerated, and after collisions with a Xenon beam we measure the fraction of OH molecules in higher rotational states. The control we have over the beam of OH radicals enables us to tune the collision energy over the energetic threshold for inelastic scattering to these states.