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

We report on a high-resolution spectroscopic survey of (LiK)-Li-6-K-40 molecules near the 2S + 4P dissociation threshold and produce a fully empirical representation for the B-1 pi 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 measurements [Ridinger et al., EPL, 2011, 96, 33001], and near-dissociation expansions for the spin-orbit coupled potentials are fitted to extract the van der Waals C-6 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 data for the B-1 pi [Pashov et al., Chem. Phys. Lett., 1998, 292, 615620] 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.

Automated summary

This study presents a high-resolution spectroscopic survey of (LiK)-Li-6-K-40 compounds, providing an empirical representation for the B-1 pi potential. The identified suitable vibrational state is significant for coherent Raman transfer and the creation of a molecular gas with dipolar interactions.