Spin—orbit coupling in the D 1Δ ∼ d 3Δ complex of 23Na39K

Abstract

A comprehensive deperturbation analysis is made of the singlet—triplet D 1Δ ∼ d3Δ complex of the 23Na39K molecule. The deperturbation model takes into account direct spin—orbit coupling between the singlet and triplet states plus a spin—rotational interaction between different Ω components of the triplet state. The direct inversion procedure provides a self-consistent set of the Dunham molecular constants for both states and for the matrix elements of the spin—orbit interaction. The deperturbation analysis is supported by electronic structure calculations performed in the framework of the relativistic effective potential method combined with many-body multipartitioning perturbation theory. The theoretical spin—orbit matrix elements agree well with their experimental counterparts.