Manipulating the motion of polar molecules with microwave radiation

Microwave radiation coupled into a cylindrically symmetric resonator is used to focus, guide, decelerate, and accelerate ammonia molecules in high-field-seeking states. In a first series of measurements, we demonstrate that the focal length of a microwave lens is directly proportional to the molecules' velocity and to the inverse of the fourth root of the microwave power. In a second series of measurements employing a modified set-up, we use a multi-stage decelerator exploiting the TE1,1,12 mode of a cylindrical resonator and various switching schemes. We can deliberately choose between spatial focusing and velocity focusing while guiding, and we demonstrate kinetic energy reduction by as much as 30% of a 12 m/s slow packet of molecules utilising the 12 deceleration stages.