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Durham e-Theses
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Ultracold Molecules: The Effect of Electromagnetic Fields

WALLIS, ALISDAIR,OWEN,GARNETT (2010) Ultracold Molecules: The Effect of Electromagnetic Fields. Doctoral thesis, Durham University.



There is great interest within the physics and chemistry communities in the properties of ultracold molecules.
Electromagnetic fields can be used to create, trap, and modify the collisional dynamics of ultracold molecules, and thus the properties of ultracold molecules in electromagnetic fields is of growing importance.

This thesis examines some of the effects of externally applied electromagnetic fields on ultracold molecules. Initially, magnetic Feshbach resonances in combined electric and magnetic fields are examined in the collisions of He($^1S$)+SO($^3\Sigma^-$).
Through detailed quantum scattering calculations, it is then shown that the sympathetic cooling of NH($^3\Sigma^-$) molecules with Mg atoms has a good prospect of success, a first for a neutral molecular system. Detailed quantum scattering calculations are performed for a wide range of collision energies and magnetic field strengths and it is found that the ratio of elastic to inelastic collisions is large for temperatures below 10 mK, and increases as the collision energy and magnetic field strength decrease. The near threshold collision properties of Mg+NH have been examined using a multichannel quantum defect theory approach.

A new type of conical intersection, that is a function of applied electromagnetic fields only, is also demonstrated. For states of opposite parity, brought into degeneracy with a magnetic field, the degeneracy can be resolved by the addition of an electric field, forming a conical intersection. A suitable arrangement of fields could thus be used to create a conical intersection in laboratory coordinates within an ultracold trapped gas.
For a Bose-Einstein condensate, in the mean-field approximation, the resultant geometric phase effect induces stable states of persistent superfluid flow that are characterized by half-integer quantized angular momentum.

Item Type:Thesis (Doctoral)
Award:Doctor of Philosophy
Keywords:"Ultracold Molecules";"Electromagnetic fields";"Sympathetic Cooling";"Conical Intersection";"Atomic and Molecular Collisions";"Feshbach Resonance";"Half Integer Quantization"
Faculty and Department:Faculty of Science > Chemistry, Department of
Thesis Date:2010
Copyright:Copyright of this thesis is held by the author
Deposited On:25 Mar 2010 15:51

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