Photoionization to the [Formula: see text] A 2Πu state and to the [Formula: see text] X 2Πg state is studied using photoelectron spectroscopy. The experimental vibrational branching ratios are obtained for the first time in the 19–34 eV region for the v′ = 0–3 levels, for both molecules. Ab initio many-body perturbation theory is used to calculate branching ratios for ionization to the [Formula: see text] A 2Πu state and branching ratios, vibrationally resolved partial cross sections and total cross section for ionization to the [Formula: see text] X 2Πg state. The Franck–Condon breakdown observed in the photoionization of the N 2 1πu electron is mainly explained by autoionization from Rydberg and valence states of N 2, whereas photoionization of the O 2πg electron is not fully explained either by channel coupling effects or by autoionization from known Rydberg series and valence states.
Channel coupling arrays and the reduction method in many-body scattering