MOLECULAR SPECTROSCOPY OF ULTRACOLD 6LI4°K MOLECULES

Abstract

This thesis reports on our experimental progress towards investigating anisotropic dipole-dipole interactions in ground state 6Li40K molecules. Evaporative cooling of 87Rb in a triple-species 87Rb-40K-6Li mixture provides sympathetically-cooled 6Li and 40K, that is subsequently magnetically associated into Feshbach molecules which we aim to coherently transfer to the absolute ro-vibrational ground state. The design and implementation of a high voltage electrode system, facilitating investigation of anisoptropic dipole-dipole interactions, is described. The implementation of 6Li D1 sub-Doppler cooling into our experiment is described, and its effectiveness evaluated. Theoretical considerations are presented on factors governing the optimal choice of starting and intermediate states for coherent state transfer, leading to two experimentally-feasible pathways to the absolute ground state being selected. A series of spectroscopic measurements are presented, comprising broad surveys of excited states on the 11Π and 21Σ potentials, followed by high resolution measurements of selected vibrational levels, as well our attempts at two-photon spectroscopy, one of which demonstrates successful addressing of the X1Σ ν=3 level.