Abstract
Near-threshold autoionization features in the photoionization spectroscopy of nitric oxide are studied by the use of the Feshbach projection-operator formalism of scattering theory. The complex autoionization structure in the photoionization spectrum of NO in the wavelength region of 1140–950 Å is described by assuming one valence state interacting with the ionization continuum and the converging Rydberg series. The strong non-Condon effects observed in the photoelectron spectra of this molecule are also discussed.