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

The electronic structure and chemical bonding of unirradiated and irradiate d Poly-1,4-phenylene-ether-sulphone (PES) films have been studied with fluo rescent X-ray emission spectroscopy. PES films have been irradiated with 15 0 keV Ar+ ions at concentrations of 5 x 10(13), 1 x 10(14), 1 x 10(15) and 7.5 x 10(15) cm(-2). The electronic structure of PES has also been calculat ed with MO LCAO calculations using a deMon density functional theory (DFT) program and shows good agreement with the experimentally obtained X-ray flu orescence spectra (S L-2,L-3, CK alpha and O K alpha). It is found that the C K alpha X-ray emission spectra (XES) of irradiated PES films display mar ked changes at very high concentrations (1 x 10(15) - 7.5 x 10(15) cm(-2)), similar to the spectroscopic characteristics of amorphous carbon. Accordin g to our measurements, the low-energy shift of the S K alpha(1,2) XES is ob served for concentrations greater than 5 x 10(13) cm(-2) which is related t o the reduction of -SO2- to -S- following the transfer of an oxygen atom fr om the -SO2- functional group to the radical site. (C) 1999 Published by El sevier Science B.V. All rights reserved.