The vibrational structure of a conjugate shake-up satellite band in the C 1s core-level photoemission of CO

The photon energy dependence of the vibrational structure of satellite bands accompanying the C 1s ionization of CO has been investigated for the first time. We have measured both photoelectron and threshold electron spectra of CO in the K-shell region, with energy resolution high enough to resolve vibrational levels. We find that a conjugate shake-up satellite shows fewer vibrational excitations around hν = 320-330 eV. This suggests that shape resonance plays an important role on vibrational dynamics in the satellite state.