Empirical LiK excited state potentials: connecting short-range and near-dissociation expansions

We report on a high-resolution spectroscopic survey of ⁶Li⁴⁰K molecules near the 2S+4P dissociation threshold and produce a fully empirical representation for the B¹Π potential by connecting available short- and long-range data. The purpose is to identify a suitable intermediate state for a coherent Raman transfer to the absolute ground state, and the creation of a molecular gas with dipolar interactions. Starting from weakly-bound ultracold Feshbach molecules, the transition frequencies to twenty-six vibrational states are determined. Our data are combined with long-range measurements¹, and near-dissociation expansions for the spin-orbit coupled potentials are fitted to extract the van der Waals C₆ dispersion coefficients. A suitable vibrational level is identified by resolving its Zeeman structure and by comparing the experimentally attained g-factor to our theoretical prediction. Using mass-scaling of the short-range data² for the B¹Π and an updated value for its depth, we model the short- and the long-range data simultaneously and produce a Rydberg-Klein-Rees curve covering the entire range. This work was recently published in PCCP³. 

¹Ridinger et al., EPL, 2011, 96, 33001

²Pashov et al., Chem. Phys. Lett., 1998, 292, 615-620

³Botsi et al., PCCP, 2022, 24, 3933 - 3940