Quantum Reactive Scattering of Ultracold NH(X3Σ-) Radicals in a Magnetic Trap

We investigate the ultracold reaction dynamics of magnetically trapped NH(X-3 Sigma(-)) radicals using rigorous quantum scattering calculations involving three coupled potential energy surfaces. We find that the reactive NH + NH cross section is driven by a short-ranged collisional mechanism, and its magnitude is only weakly dependent on magnetic field strength. Unlike most ultracold reactions observed so far, the NH + NH scattering dynamics is nonuniversal. Our results indicate that chemical reactions can cause more trap loss than spin-inelastic NH + NH collisions, making molecular evaporative cooling more difficult than previously anticipated. DOI: 10.1103/PhysRevLett.110.063201