Investigating ultracold alkali halide molecules

The thesis explores small triatomic and diatomic alkali halide molecules at state specific resolution at ultracold regime. Ab initio calculations are carried out to further publishable data to attempt a global potential energy surface for both LiF and LiCl, reacting with an approaching Li atom. Potential curve dynamics for both reactions, including well depths, avoided crossings and barrier heights are calculated to SA CASSCF and CCSD(T) level using an A VTZ basis set on all four states. This methodology is repeated as a function of the diatomic bond length. Both reactions are then compared to investigate the impact of substituting the halide. The smaller diatomic alkali halide cations are calculated up to MRCV(Q) level with basis sets ranging from A VQZ-A V6Z. Potential energy curves and dipole moments, (both permanent and transition) are calculated for the four energy states for the alkali halide series and are compared between the four molecules under examination; including LiF+, LiC\+, NaF+ and NaCl+. These curves are then fitted and inputted into LEVEL 8.0 to calculate a wealth of information including rotational and rotational constants, bound vibrational levels, Franck Condon factors and Einstein A coefficients. These findings could potentially aid in identifying the alkali halide products under Resonance Enhanced Multi Photon Ionization (REMPI).EThOS - Electronic Theses Online ServiceGBUnited Kingdo