X-ray, ultraviolet, and synchrotron radiation excited inner-valence photoelectron spectra of CH4

The inner-valence electron states of the methane molecule have been studied by means of x-ray, synchrotron radiation, and UV-photoelectron spectroscopy. Five correlation satellites have been identified and a detailed study has been carried out of the 2a−11 single hole state. For this state a Franck–Condon analysis has been performed, suggesting an equilibrium bond distance of 1.279 Å. The vibrational lines have a Lorentzian shape and the linewidth increases gradually with the vibrational quantum number. This probably indicates a reduction of the lifetime of the vibrational states due to predissociation. A discussion of the potential curves related to the correlation satellites is included.