Photoionization processes in NO in the threshold region

The photoion excitation spectrum of NO has been measured in the 9.26–13.8 eV region using synchroton light and the isotopic targets 14N16O, 15N16O and 15N18O. The resulting complex spectra have been interpreted using ab initio results based on many-body theory. The ab initio predictions suggest that the structure follows from autoionizations of four repulsive valence states of 2Σ symmetry and interactions between an attractive 2δ valence state and Rydberg series converging to the NO+ ground state.