We examine the quenching reaction Rb (doublet S) + NH (singlet Delta) goes to Rb (doublet P one-half) + NH (ground triplet Sigma minus). This reaction may be utilized to produce ground state NH molecules for studies of ultracold physics or for other
purposes, and is interesting in that it involves initial and final states that are nearly degenerate. This near degeneracy is expected to lead to a large reaction rate. We examine this system using ab initio quantum chemistry calculations and scattering calculations, which include spin-orbit effects, and find that the reaction rate is large and, in fact, approaches the quantum mechanical unitarity limit. We discuss the prospects for an experimental examination of this system.
