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Title: Creation of ultracold RbCs molecules
Author: Köppinger, Michael Peter
ISNI:       0000 0004 5366 1742
Awarding Body: Durham University
Current Institution: Durham University
Date of Award: 2014
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This thesis reports the investigation of the scattering properties of a mixture of Rb and Cs and the formation of ultracold Feshbach molecules. The production of Feshbach molecules is a crucial step towards the production of ultracold polar molecules, which is of significant interest for a wide range of potential applications. We have investigated the scattering properties of a mixture of ⁸⁵Rb and ¹³³Cs in their lowest spin channel in a magnetic field range from 0 to 700 G. Furthermore, we explored the Feshbach spectrum of ⁸⁵Rb alone in both, the (f = 2,mf = -2) and (2,+2) states up to a magnetic field of 1000 G. Additionally a Feshbach resonance in a (2,+2)+(3,+3) spin mixture was experimentally confirmed. We associated Cs₂ Feshbach molecules using a Feshbach resonance at 19.9 G. 2.1(1) x 10⁴ molecules with a temperature of ~ 60nK were produced from a sample of 3.28(2) x 10⁵ Cs atoms with a PSD of 0.20(1). Due to a magnetic field gradient, the molecules 'bounce' at an avoided crossing between two states at 13.5G. This gradient field was also used to produce multiple molecular clouds from one atomic sample. A combination of both techniques led to a 'collision' between two Cs₂ clouds. Furthermore, we associated up to ~ 5000 heteronuclear ⁸⁷RbCs Feshbach molecules using an interspecies resonance at 197.1G. Confined in the dipole trap the molecules have a lifetime of 0.21(1)s. We have measured the magnetic moment of the molecules in different internal states in a magnetic field range from 181 to 185G. Molecular loss spectroscopy on electronically excited states was performed to identify candidates for the intermediate state of a STIRAP transfer of the molecules into their rovibrational ground state. Subsequently, the binding energy of the rovibrational ground state was measured to be 3811.574(1)cm⁻¹, using two-photon spectroscopy.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available