Structure, and the laser cooling scheme for the XF− (X=Li, Na, K, Rb) molecule

[Display omitted] •Transition dipole moments, Franck-Condon factors, and radiative lifetimes were investigated.•The spin-orbit coupling effect was calculated based on the CASSCF/MRCI+Q method.•The quasi-closed energy level system is constructed for laser cooling of the XF− (X=Li, Na, K, Rb) anion. For laser-cooling considerations, we have theoretically investigated the electronic structures of the XF− (X=Li, Na, K, Rb) molecule. The potential existence of anions is initially examined through the analysis of their affinity energies and dipole moments of the corresponding neutral molecules. Subsequently, we excluded the effect of spin–orbit coupling on the molecular. Then the calculations reveal that XF− (X=Li, Na, K, Rb) exhibits a highly diagonalized Franck-Condon factor and a short spontaneous radiation lifetime, facilitating the design of laser cooling schemes for each molecular ion. The findings provide an important reference for laser cooling experiments involving alkali metal fluoride anions.