Effects of spin–orbit coupling on the coupled 33Π and 43Π excited states of NaK

Abstract Spin–orbit coupling constants calculated for several excited states of the NaK molecule are used to interpret recent experiments. The theoretical results, which provide coupling constants as a function of internuclear separation R , were convoluted with vibrational wavefunctions in order to determine vibrational-state-dependent spectroscopic constants that could be compared with recent measurements for the 3 3 Π state. Sharp structure in the experimental data could be attributed to rapid changes in the adiabatic spin–orbit coupling near an avoided crossing.