Deceleration and trapping of ammonia using time-varying electric fields

A polar molecule experiences a force in an inhomogeneous electric field. Using this force, neutral molecules can be decelerated and trapped. It is shown here that this can in principle be done without loss in phase-space density. Using a series of 64 pulsed inhomogeneous electric fields a supersonic beam of ammonia molecules (^14NH₃, ^14ND₃, ^15ND₃) is decelerated. Subsequently, the decelerated molecules are loaded into an electrostatic quadrupole trap. Densities on the order of 10^7 molecules/cm^3 at a temperature of 25 mK are obtained for ^14ND₃ and ^15ND₃ separately and simultaneously. This corresponds to a phase-space density in the trap of 210^-13, 50 times less than the initial phase-space density in the beam.