Lifetime studies of the NH molecule: New predissociations, the dissociation energy, and interstellar diatomic recombination

Previously unknown predissociations in the NH radical have been discovered via high resolution lifetime measurements using the high-frequency deflection technique. Measurements were made for individual rotational levels for ν′=0 and ν′=1 for the NH A ³Π and the c ¹Π states. The origin of the observed predissociation is indicated to be the ⁵Σ^- level arising from the ground state asymptote. These data allow a determination of the dissociation energy of the ground state and the singlet-triplet manifold separation. Implications of these results for the astrophysical abundance of NH formed by radiative recombination processes are discussed.