Feshbach resonances in Na 23 + K 39 mixtures and refined molecular potentials for the NaK molecule

We present a detailed study of interspecies Feshbach resonances of the bosonic Na23+K39 mixture for magnetic fields up to 750G in various collision channels. A total of 14 Feshbach resonances are reported, as well as four zero crossings of the scattering length and three inelastic two-body loss features. We use the observed magnetic-field locations of the resonant features together with the known data on Na23+K40 to refine the singlet and triplet ground-state potentials of NaK and achieve a consistent description of Feshbach resonances for both the Bose-Bose mixture of Na23+K39 and the Bose-Fermi mixture of Na23+K40. We also discuss the influence of the interplay between inelastic two-body and three-body processes on the observation of a Feshbach resonance.