X-Ray Photoelectron Spectroscopy of the Molecules Containing the C≡N Group

Abstract The gas-phase X-ray photoelectron spectra (with MgKα radiation) were observed on acetonitrile, propionitrile, acrylonitrile and fumaronitrile. The ionization potentials were determined for all valence-electron levels of the above molecules by using the data derived from the observed valence-electron bands of X-ray photoelectron spectra and the reported data of ultraviolet photoelectron spectroscopy. It is shown that there is a linear relation between the observed ionization potential (IP) and the CNDO/2 orbital energy (ε): IP=0.61(−ε)+3.2[eV], for σ-orbitals; IP=0.38(−ε)+6.0[eV], for π-orbitals. The observed binding energies of the C ls levels were analyzed by means of the electrostatic potential model and the charge densities calculated by CNDO/2 method. Discussion is given also on the shake-up satellite of core-electron peak.