Spectra analysis of the XPS core and valence energy levels of polymers by an ab initio mo method using simple model molecules

Abstract

The X-ray photoelectron spectra (XPS) of polyacrylic acid (PAA), polyvinyl acetate (PVAc), and polymethyl methacrylate (PMMA) were analyzed by an ab initio MO method using molecules of 1,3,5-hexanetricarboxylic acid (HCA), 1,3,5-triacetoxy hexane (TAH), and dimethyl 2-methylpentane 2,4-dicarboxylate (MMPC), respectively. The theoretical spectral patterns derived from the Gelius-Siegbahn model showed good agreement with the spectra observed between 0–30 eV. The present results suggest several new assignments for the XPS spectra. The valence-level O2 s spectra of the polymers at around 27 eV correspond to sσ (O2 s-C2 s)-bonding and pσ (O2 s-C2 p)-bonding orbitals arising from the -O- and OC< groups. For PMMA, the broader core-level Cl s spectra at around 285.0 eV were found to be due to four components, -O-CH 3, >C<, -CH 2 and -CH 3, respectively.