Low-energy negative-ion states of NO at high electron energy resolution

Low-energy resonances involving the 3Σ−, 1Δ and 1Σ+ states of NO− have been studied by high-resolution electron scattering integrated over the angular range 60–120° and in the energy range 0.07–1.6 eV. The resonant vibrational energies of the 3Σ− state yield agreement with the NO electron affinity of 24 meV determined from photodetachment studies. The widths of the vibrational series 3Σ− and 1Δ increase slowly with the vibrational quantum number at variance with calculations.