Influence of magnetic fields on cold collisions of polar molecules

We consider cold collisions of OH molecules in the 2P3/2 ground state, under the influence of a magnetic field. We find that modest fields of several thousand gauss can act to suppress inelastic collisions of weak-field-seeking states by two orders of magnitude. We attribute this suppression to two factors: (i) an indirect coupling of the entrance and the exit channel, in contrast to the effect of an applied electric field; and (ii) the relative shift of the entrance and exit scattering thresholds. In view of these results, magnetic trapping of OH may prove feasible