Increased Control over Reaction Conditions in a Hybrid Trap

This thesis presents work towards increased control over reaction conditions in a hybrid trap, which is composed of an ion trap spatially overlapped with a magneto-optical trap (MOT).
A novel type of hybrid trap is presented with the aim to increase the control over collision energies. As normally on our setup both the neutral and ionic species are continuously cooled, collision energies are low and hard to control. To solve this problem, a dynamic MOT was created, where an atom cloud is shuttled between two off-center positions within the trap. A detailed description of the new hybrid trap setup is presented. The generation of the MOT laser light and its manipulation inside an acousto-optical modulator setup driven by a home-built radio-freequency setup is discussed. The shuttling atom cloud was analysed by time-of-flight experiments, which were compared to results from Monte Carlo trajectory simulations. During reaction measurements, the atoms can be moved at velocities of 3.1 to 4.8 m/s, corresponding to kinetic energies of the rubidium atoms of Ekin = 50 mK to 120 mK.
For the ions, work towards implementing vibrationally state-selected molecular oxygen ions is presented. Ions were produced by resonant multiphoton ionisation and spectroscopy was performed on the 3dδ ³Φ Rydberg states. First reactions of molecular oxygen ions in the vibrational ground state with a stationary atom cloud were measured. It was found that the reaction rate did not depend on the excited state fraction of the rubidium atoms. This was rationalised with the crossing of the potential energy surface of a charge-transfer exit channel close to the potential minimum of the ground-state entrance-channel potential energy surface.