Creation of ultracold RbCs molecules

Abstract

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 Rb and Cs in their lowest spin channel in a magnetic field range from 0 to 700G. Furthermore, we explored the Feshbach spectrum of Rb alone in both, the and states up to a magnetic field of 1000G. Additionally a Feshbach resonance in a spin mixture was experimentally confirmed.


We associated Cs Feshbach molecules using a Feshbach resonance at 19.9G. molecules with a temperature of nK were produced from a sample of 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 Cs clouds.


Furthermore, we associated up to heteronuclear RbCs 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, using two-photon spectroscopy.