[en] Building on our previous work on the three photon multiphoton ionization spectrum, we have examined the MPI-PE spectra for carbon dioxide with a view toward seeing whether the nuclear dynamics of a resonant excited state will influence the multiphoton ionization process. In the case of at least one resonance, the 3pσ ¹Π_u Rydberg state, a very dramatic example of ATI is found. We have measured the multiphoton ionization spectra of nitrogen molecules which have passed through an electric discharge in a supersonic beam. We have been able to get higher quality spectra and to observe several transitions which we did not see in our previous study. It is hoped that these new peaks and the higher quality spectra will lead to a breakthrough in the analysis of the many unassigned peaks in the spectra. 8 refs., 2 figs