Spectra analysis of XPS valence energy levels of polymers by the semi-empirical MO method—I. Polyvinylalcohol, polyethyleneoxide and polyvinylchloride

Abstract

Electronic spectra of XPS valence energy levels (0–50 eV) of Polyvinylchloride (PVC), polyethyleneoxide (PEO) and polyvinylalcohol (PVA) were analyzed by a semi-empirical PM3 MO method using a crystal model of one-dimensional periodicity. The three stereoisomers of PVC and PVA were calculated using the MO method and the probability for the existence of these isomers was estimated from the 1H and 13C NMR spectra. The theoretical spectral patterns derived from the Gelius-Siegbahn model showed good agreement with the spectra observed between 0 and 30 eV. Our results suggest several new assignments for the XPS spectra. The spectra below 18 eV correspond to the valence band which exhibits splitting intensity patterns of many adjacent MO energy levels due to the valence p contribution. The lifetime of the ionized states in the inner valence region (20–35 eV) of the s contribution was estimated to be of the order of 10 −15 s.