Our research uses supersonic expansion coupled with Stark deceleration to cool and slow polar molecules. We start by expanding a mixture of Krypton and the molecule of interest through  a small aperture into our vacuum system. The resulting pulse of ground-state molecules has a narrow velocity distribution in three dimensions and a mean longitudinal velocity of several hundred meters per second.

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The next step is to slow the molecules into the rest frame of the laboratory. After the expansion, the molecular pulse propagates through a skimmer, which allows for differential pumping between vacuum chambers. The molecules then fly into the entrance of the Stark decelerator. The geometry of the electrodes that make up the decelerator, creates a maximum of electric field in the longitudinal direction directly between an electrode pair. As the molecules propagate into this increasing electric field they loose longitudinal kinetic energy. If the molecules were allowed to continue down the potential hill they would regain the lost kinetic energy; however, before they begin to accelerate, the electric field is instantaneously turned off, thus removing energy from the molecules. This process is repeated with successive stages of electrodes until the molecules have been sufficiently slowed to be loaded into a magnetic trap. Additionally, transverse guidance of the molecules is achieved because the molecules are attracted to the minimum of electric field along the center of the decelerator. Successive electrode pairs are orientated orthogonally to one another to guide the molecules equally in both transverse dimensions.

Molecular Beam

Once the molecules have been slowed to near zero velocity, they can be trapped by either static magnetic or electric fields. One goal is to observe and control molecular interactions in an unexplored temperature regime.