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

Abstract

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: r_NH=1.0367(154), θ_HNH=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.