Laser cooling with intermediate state of spin-orbit coupling of LuF molecule.

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.