Symmetry and vibrationally resolved absorption spectra near the N K edges of N2O : experiment and theory

In this study, angle-resolved energetic-ion yield spectra were measured in the N 1s excitation region of N2O. A Franck-Condon analysis based on ab initio two-dimensional potential energy surfaces of the core-excited Rydberg states, which were calculated by the symmetry-adapted cluster-configuration interaction method, reproduced observed vibrational excitations specific to the individual Rydberg states well and enabled quantitative assignments. Geometric changes in the terminal nitrogen N-t 1s and the central nitrogen N-c 1s excited states with respect to the 3p pi, 3p sigma, and 4s sigma transitions were analyzed. The coupling of these valence and Rydbergs states was examined based on the second moment analysis. Irregular Rydberg-state behavior in the N-c 1s(-1) 4s sigma state was observed