Angle-resolved ion-yield measurements of CO2 in the O 1s to Rydberg excitation region

Angle-resolved energetic-ion-yield spectra were observed in the region of the O 1s to Rydberg excitation of CO2 with incident photon energy resolving power E/ΔE≃14 000. The assignments of the electronic states were established in accordance with the angular distribution data. All the observed vibrational structures were assigned to the antisymmetric stretching vibrations caused by the vibronic coupling between the nearly degenerate O 1s core-excited states. A Franck-Condon analysis was performed within the linear coupling model.