Core-valence multiply excited states in N₂ probed by detecting metastable fragments

Angle-resolved metastable fragment yields following photo-excitation have been measured in the photon energy region 405.7-430 eV in N₂. Structures corresponding to multiple excitations associated with parallel and perpendicular transitions are observed in the metastable yield curves recorded using detectors orientated at 0° and 90° to the electric field vector of the linearly polarized incident radiation. The double-excitation structures around 415 eV are interpreted in terms of the overlap of three broad peaks and vibrational progressions. Multiple excitation structures corresponding to high Rydberg states converging to N⁺₂ shake-up satellites are seen above 418 eV. The present work demonstrates that the angle-resolved detection of metastable fragments is an effective spectroscopic tool for probing core-valence multiply excited states in molecules.