Simulation of the Valence X-Ray Photoelectron Spectra of 16 Polymers by the Semiempirical HAM/3 MO Method Using the Model Molecules

Abstract

The HAM/3 method was used to provide a better assignment of the valence X-ray photoelectron spectra of 16 polymers involving nitrogen, oxygen, fluorine, a glucose unit, and a benzene nucleus using the monomer, dimer or trimer model molecules without consideration of the contraction factor of the energy scale. The calculated Al Kα photoelectron spectra were obtained using Gaussian functions of a fixed approximate linewidth, 0.10 I_k and I_k = I′_k − WD, where I′_k is the vertical ionization potential of each MO and WD is an approximate shift to account for the work function of the sample and other energy (polarization energy and so on) effects. We assumed that WD corresponds to the shift that we must apply before we can compare the calculated spectrum for the single model molecule with the observed spectrum for the solid. The approximate linewidth corresponds to the experimental result that the inner valence spectra are broader. The theoretical spectra showed good agreement with the spectra of the polymers observed between 0—40 eV.