Photon energy dependence of the high resolution C 1s photoelectron spectrum of CO in the threshold region.
The C 1s photoelectron spectrum of CO has been measured with high resolution in the threshold region. The data exhibit hitherto unresolved vibrational structure on the C 1s main photoelectron line as well as new features in the satellite region. The vibrational energy of the CO + ion is 301±3 meV. The vibrational structure changes dramatically with photon energy due to the influence of the σ * shape resonance. The new satellite lines which are not present at high photon energies are attributed to conjugate shakeup processes