Spin-orbit coupling in the D-1 Pi similar to d(3)Pi complex of (NaK)-Na-23-K-39

A comprehensive deperturbation analysis is made of the singlet-triplet D(1) Pi similar to d(3)Pi complex of the (NaK)-Na-23-K-39 molecule. The depertur bation model takes into account direct spin-orbit coupling between the sing let and triplet states plus a spin-rotational interaction between different Omega components of the triplet state. The direct inversion procedure prov ides a self-consistent set of the Dunham molecular constants for both state s and for the matrix elements of the spin-orbit interaction. The deperturba tion analysis is supported by electronic structure calculations performed i n the framework of the relativistic effective potential method combined wit h many-body multipartitioning perturbation theory. The theoretical spin-orb it matrix elements agree well with their experimental counterparts.