Vibrational autodetachment of NO−

We report infrared cross sections for the photodetachment of the molecular anion NO− in the energy range of 1100–1500 cm−1. The measurements are made with a coaxial ion beam–laser beam aparatus. We observe a vibrational autodetachment resonance centered at 1284±10 cm−1. The resonance has a full width at half-maximum of 170 cm−1 corresponding to a lifetime of 0.35×10−12 s for NO−(v=1). The present value for the vibrational frequency of NO− is significantly lower than previous estimates obtained from photoelectron spectroscopy of NO− and from electron scattering resonances in NO. We discuss the implications of our results with regard to previous measurements of infrared photodetachment cross sections in the region 3000–4100 cm−1.