Magnetic trapping of molecules via optical loading and magnetic slowing

This thesis demonstrates a new cooling and trap loading technique for molecules, leading to trapping of calcium monofluoride (CaF). Two key principles developed and used are a very slow molecular beam and irreversible loading of a magnetic trap via optical pumping. The cooling of molecules occurs inside a cryogenic buffer-gas cell, where collisions between the molecules and cold, inert buffer gas cool the initially hot molecules.;Cold molecules emitted out the cell through an exit aperture enter another slowing cell with a piece of mesh on the final exit aperture. Such a two-stage cell provides slow monohydride (CaH) molecules with a moving velocity of 60 m/s and a flux of 109 molecules/pulse.;This technique is completely general, and is applied to produce slow beams of atomic potassium and CaF. We direct a slow CaF beam with vf N=1, with a trap lifetime exceeding 500 ms. Trajectory simulations are developed to optimize the loading process and simulate the loss of trapped molecules. The attained trap lifetime is limited by elastic collisions with the background 3He gas at a density of 5x10 10 cm-3. Using this new loading method, we also realized trapping of CaF (N=0) and CaH (N=0). This work provides the platform for future work. We plan to co-load CaH molecules with Li atoms to study cold collisions and cold controlled chemistry inside the trap, which may shed the light on further cooling of molecules using Li as the coolant. Laser cooling of trapped CaF (N=1) may be feasible inside the trap. Magnetic trapping of chemically diverse molecules without closed cycling transitions, including triatomic molecules, may be realized with the scattering of only a few photons.