THE ABSORPTION-COEFFICIENT SPECTRUM AND RADIATION DEGRADATION OF POLY(BUTENE-1 SULFONE) IN THE SOFT-X-RAY REGION

The interaction of soft x-rays with poly (butene-1 sulfone) (PBS) has been examined in detail, using monochromatized synchrotron radiation f rom the Canadian Synchrotron Radiation Facility (CSRF). The total phot oabsorption cross section and neutral fragment yields of poly(butene-1 sulfone) (PBS) were measured over the photon energy range 20 less-tha n-or-equal-to hv less-than-or-equal-to 1000 eV. Energy deposition in t his energy region results primarily in mass loss due to depolymerizati on. The chemical byproducts were detected using an in situ mass spectr ometer. The experimental absorption data was corrected for spectral co ntamination of the incident monochromator radiation through the use of calculated photoabsorption cross sections. The calculations incorpora ted reliable dipole oscillator strength distributions of smaller molec ules chemically related to PBS as input, and the results are reliable over the absorption regions away from the, edges. The corrections thus applied to the initial experimental data have produced the most relia ble spectrum available presently for PBS. The near-edge extended x-ray absorption fine structures (NEXAFS) were measured and assigned for th e sulfur 2p (L2,3), carbon 1s (K) and oxygen 1s (K) edges. The sulfur 2p edge of PBS was found to be very similar to that found in the photo absorption spectrum of gaseous SO2, particularly in the continuum regi on. The two broad peaks in the continuum have been assigned as sigma- shape resonances caused by a centrifugal potential barrier. Ionization of the valence orbitals of PBS produced a significant increase in the depolymerization reaction, and subsequent neutral yields of sulfur di oxide (SO2) and 1-butene. (C) 1993 John Wiley & Sons, Inc.