Shake-up and photoelectron-impact mechanisms of the satellite excitations in the molecular core level photoemission

Low-energy satellite bands accompanying the C 1s mainline have been investigated both for randomly-oriented and fixed-in-space CO2 molecules. We find that these satellite bands are resonantly enhanced at the same photon energy as the shape resonance of the mainline and more enhanced for the E-symmetry parallel transition than the II-symmetry perpendicular transition. Our observations contradict the predictions based on the shake-up model and agree with predictions given by the photoelectron-impact model which assumes the dominance of final state correlations arising from the interaction between a primary photoelectron and a valence electron.