Fine structure investigation and laser cooling study of the LaH molecule

Abstract

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 X³Σ₀₊, (1)³Π₀₊, and (1)³Δ₁ predicts the candidacy of the molecule LaH for direct laser cooling between the first two states with the intermediate state (1)³Δ₁. 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.