Radiation-induced degradation of polyethersulphone films studied by fluorescent X-ray emission spectroscopy

Abstract

The electronic structure and chemical bonding of unirradiated and irradiated Poly-1,4-phenylene-ether-sulphone (PES) films have been studied with fluorescent X-ray emission spectroscopy. PES films have been irradiated with 150 keV Ar + ions at concentrations of 5 × 10 13, 1 × 10 14, 1 × 10 15 and 7.5 × 10 15 cm −2. The electronic structure of PES has also been calculated with MO LCAO calculations using a deMon density functional theory (DFT) program and shows good agreement with the experimentally obtained X-ray fluorescence spectra (S L 2,3, C Kα and O Kα). It is found that the C Kα X-ray emission spectra (XES) of irradiated PES films display marked changes at very high concentrations (1 × 10 15 − 7.5 × 10 15 cm −2), similar to the spectroscopic characteristics of amorphous carbon. According to our measurements, the low-energy shift of the S Kα 1,2 XES is observed for concentrations greater than 5 × 10 13 cm −2 which is related to the reduction of –SO 2– to –S– following the transfer of an oxygen atom from the –SO 2– functional group to the radical site.