Velocity modulation infrared laser spectroscopy and structure of the amide anion (NH−2 )

The vibration–rotation spectrum of the amide anion (NH−2 ) has been measured in the 3 μm region by velocity modulation laser spectroscopy. The ν1 and ν3 bands have been simultaneously fit to a Watson S reduced Hamiltonian; the band origins are (in cm−1) 3121.9306(61) and 3190.291(14), respectively. The r0 structure has been determined: rNH=1.0367(154), θHNH=102.0(3.3). Under appropriate discharge conditions, NH−2 concentrations near 4×1011 molecules/cm3 can be produced in cells with metal-coated walls. Comparisons with condensed phase measurements and ab initio calculations are presented.