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\We report results on pulsed field ionization of NO and O2. The experiments were carried out using tunable coherent vacuum ultraviolet radiation for single photon excitation of the NO or O2 molecules. In the case of NO, light between 15.66 eV and 15.90 eV was used to probe the v equals 0, 1, and 2 levels of the NO+(a3(Sigma) +) state. The resulting PFI-ZEKE spectra were interpreted using a model developed to explain rotational line intensities in photoelectron spectra. The rotational line intensities were found to vary systematically with v+, in disagreement with the model, and the intensities in the v+ equals 1 band were strongly affected by the presence of a complex resonance at that energy. In addition, the relative intensities of the v+ equals 0, 1, and 2 bands were very different from the Franck-Condon factors, with the intensity of the v+ equals 1 band strongly enhanced by the complex resonance, and the v+ equals 2 band having a much smaller intensity than expected. In oxygen, we were able to record rotationally resolved PFI-ZEKE spectra of the v+ equals 6 to 21 vibrational levels of the O2+(X2$PRDg) electronic state. As these levels have zero Franck-Condon factors with O2(X3(Sigma) g+)(v equals 0), their observation shows the presence of a type of `resonant autoionization,' where neutral continuum states provide a coupling between Franck-Condon allowed Rydberg states and the Franck-Condon forbidden levels observed.
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