Laser cooling with intermediate state of spin–orbit coupling of LuF molecule

Abstract This work presents a theoretical study of the laser cooling feasibility of the molecule LuF, in the fine structure level of approximation. An ab-initio complete active space self-consistent field (CASSCF)/MRCI with Davidson correction calculation has been done in the Λ (±) and Ω (±) representations. The corresponding adiabatic potential energy curves and spectroscopic parameters have been investigated for the low-lying electronic states. The calculated values of the internuclear distances of the X 3 Σ 0+ and (1) 3 Π 0+ states show the candidacy of the molecule LuF for direct laser cooling. Since the existence of the intermediate (1) 3 Δ 1 state cannot be ignored, the investigation has been done by taking into consideration the two transitions (1) 3 Π 0+ −(1) 3 Δ 1 and (1) 3 Π 0+ −X 3 Σ 0+ . The calculation of the Franck–Condon factors, the radiative lifetimes, the total branching ratio, the slowing distance, and the laser cooling scheme study prove that the molecule LuF is a good candidate for Doppler laser cooling.