Near-threshold photodetachment spectroscopy and THz spectroscopy of NH$^{-}_{2}$

NH$^{-}_{2}$ ions are known to be interesting species for understanding interstellar nitrogen chemistry [1]. Recent astronomical observations showed that an unidentified absorption feature at 933.973-934.009 GHz might be associated to p-NH$^{-}_{2}$ [1]. We, therefore, present findings on near-threshold photodetachment spectroscopy of the amide anion NH$^{-}_{2}$ performed in a cold (10 K) 22-pole ion trap. The spectrum reveals step features which are associated with specific transitions between rotational levels of the ground vibrational state of NH$^{-}_{2}$ (X$^1$A$_1$ electronic state) and NH$_2$ (X$^2$B$_1$ electronic state). With this data we can significantly improve the determination of the electron affinity of amidogen NH$_2$ and access the fundamental rotational transition of p-NH$^{-}_{2}$. [1] C. M. Persson, M. Hajigholi, G. E. Hassel, A. O. H. Olofsson, J. H. Black, E. Herbst, H. S. P. M\"{u}ller, J. Cernicharo, Wirstr\"{o}m, M. Olberg, \AA. Hjalmarson, D. C. Lis, H. M. Cuppen, M. Gerin, and K. M. Menten 2014 \emph{Astronomy \& Astrophysics}