New Spectroscopic Data and Analysis of Existing Data on the $A^{1}\Sigma^{+}$ and $b^{3}\Pi$ states of NaK

Current efforts to produce cold NaK molecules\footnote{M. Zwierlein, private communication.} by excitation from Feshbach resonance states and stimulated decay require an accurate model of the energy level structure of the species. There have been numerous publications over the past 25 years with high quality spectroscopic data, but gaps remain, and there is no systematic compilation for the NaK A and b states. We have obtained new data that fill some of the gaps and provide more information on perturbation interactions between these states, and we have constructed a model based on direct fits to potentials and spin-orbit coupling elements. We will present results and discuss possible interactions with the NaK $c^{3}\Sigma^{+}$ state.