Satellite structure in the x-ray photoelectron spectra of gaseous furan, pyrrole, and thiophen

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Abstract
The intensities and energies of satellite peaks in the x‐ray photoelectron spectra of gaseous furan, pyrrole, and thiophen have been measured. Because contributions owing to inelastic scattering of the electrons can be minimized in the gas phase, these investigations give a clearer picture of the satellite structure than do previously reported measurements in the solid phase. CNDO/2 wavefunctions have been used to predict both energies and intensities of the satellite peaks. Although there is qualitative agreement between theory and experiment, quantitative agreement is lacking. The theoretical calculations show that low‐energy satellites are those involving transitions from occupied to unoccupied π orbitals. The calculated wavefunctions provide information on charge rearrangement during photoionization. In particular, it is found that not only is there transfer of charge from the heteroatom to the carbons during shake up (expected from properties of the neutral molecule), but also there is charge transfer away from the core hole. Accurate core ionization potentials are reported for these molecules in the gas phase.