Feshbach resonances in 23Na-87Rb

We describe s-wave collisions between ultracold Na-23 and Rb-87 atoms in the presence of a magnetic field. For any collision input channel knowledge of the singlet and triplet intermolecular potentials [1] enables us to predict the variation in scattering lengths as a function of the magnetic field. We employ the Born-Oppenheimer approximation to predict several Feshbach resonances for Na-23 Rb-87. We also include a discussion of why these resonances are expected to be narrow as observed in the case of Rb-87(2).