The study of chemical reactions in the finest detail, in cold collisions, offers far-reaching prospects in the fields of atomic and molecular physics, as well as the growing field of cold chemistry. The precise manipulation of the internal and external states of atoms and molecules allows unprecedented control over reaction processes. Also, influence over chemical pathways is crucial for potential applications to quantum information processing. This thesis focuses on the inelastic processes of charge transfer and radiative association in the [NaCa]^+ and [YbRb]^+ systems in the ultracold regime. These systems offer the possibility of microscopic manipulation of quantum coherences in a quantum gas, using the ion as a probe. However, ion loss from the inelastic processes can be significant, and the rate coefficient for ion loss has been measured experimentally for a Yb^+ ion immersed in Rb vapour. This thesis uses calculations from first principles to study different hybrid systems, and determines from them useful properties, including the potential energy curves, dipole moments, 'spectroscopic molecular constants, dispersion coefficients and scattering lengths for the lowest-lying energy states. The cross sections and rate coefficients for the total radiative decay processes are obtained using several different approaches, and the results are examined for a wide range of collision energies, with a particular focus on experimentally accessible energies. Consistency with experimental findings and former theoretical studies is examined, and the implication of discrepancies is discussed. This work thus provides the ongoing investigation of ultracold ion-atom hybrid systems and the broader field of ultracold chemistry with vital information needed for cooling processes like the sympathetic cooling of ions using a buffer gas of ultracold alkali atoms. In the field of quantum information processing, studies of this nature could prove especially useful in the cooling of qubits to maintain their quantum coherence
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:679214 |
| Date | January 2015 |
| Creators | Lamb, Hugo Dominic Llewellyn |
| Publisher | Queen's University Belfast |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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