David Glenn

The study of ultracold dipolar molecules is an important emerging frontier in atomic physics. This thesis discusses the development of techniques for cooling diatomic molecules, focussing specifically on the idea of using a microwave frequency quasi-optical dipole trap for evaporative cooling. A prototype for such a trap has been designed, constructed, and tested. In order to load the microwave trap, a helium buffer gas cooled molecular beam source has been developed and characterized - in a variety of flow regimes, ranging from the effusive (thermal mean velocity, moderate flux), to the deeply hydrodynamic (large forward velocity, high-flux, high collimation). We explain the development of this source in detail. In particular, we describe recent work towards demonstrating direct laser cooling of a hydrodynamic SrF molecular beam. We have identified a set of quasi-closed transitions which should enable more than 104 photon scattering events, sufficient to decelerate a hydrodynamic beam to the Doppler limit. We present experimental results demonstrating optical deflection of a SrF beam by radiative force using this scheme, in which each molecule scatters on the order of 150 photons, limited by its interaction time with the lasers