Structures, Branching Ratios and Laser Cooling Scheme for 138BaF Molecule

TL;DR

This paper provides a comprehensive theoretical analysis of the BaF molecule's electronic and rovibrational structures, branching ratios, and hyperfine splittings, facilitating future laser cooling and trapping experiments.

Contribution

It offers detailed calculations of Franck-Condon factors, branching ratios, state mixing, and hyperfine structures, which are novel benchmarks for BaF laser cooling schemes.

Findings

High diagonal Franck-Condon factors enable efficient cooling transitions

Calculated branching ratios identify optimal cycling transitions

Hyperfine and Zeeman parameters inform laser polarization choices

Abstract

For laser cooling considerations, we have theoretically investigated the electronic, rovibrational and hypefine structures of BaF molecule. The highly diagonal Franck-Condon factors and the branching ratios for all possible transitions within the lowest-lying four electronic states have also been calculated. Meanwhile, the mixing between metastable A'2{\Delta} and A2{\Pi} states and further the lifetime of the {\Delta} state have been estimated since the loss procedure via {\Delta} state would like fatally destroy the main quasi-cycling {\Sigma}-{\Pi} transition for cooling and trapping. The resultant hyperfine splittings of each rovibrational states in X2{\Sigma}+ state provide benchmarksfor sideband modulations of cooling and repumping lasers and remixing microwaves to address all necessary levels. The calculated Zeeman shift and g-factors for both X and A states serve as benchmarks for selections of the trapping laser polarizations. Our study paves the way for future laser cooling and magneto-optical trapping of the BaF molecule.