Fine structure investigation and laser cooling study of the LaH molecule

A theoretical feasibility study of the spin-orbit laser cooling of the molecule LaH has been performed based on a complete active space self-consistent field (CASSCF)/MRCI ab initio calculation with Davidson correction in the Λ ^(±) and Ω ^(±) representations. The adiabatic potential energy curves and spectroscopic constants have been investigated for the considered electronic states. The small value of the equilibrium positions difference ΔR _e between the ground and the electronic states X ³ Σ ₀₊, (1)³ Π ₀₊, and (1)³ Δ ₁ predicts the candidacy of the molecule LaH for direct laser cooling between the first two states with the intermediate state (1)³ Δ ₁. The calculation of the diagonal Franck-Condon factors, the short radiative lifetime, and the experimental parameters (slowing distance, Doppler and recoil temperature, …) suggest that the molecule LaH is a good candidate for Doppler laser cooling, and a corresponding laser cooling scheme is presented.