Modifications in the chemical bonding and optical absorption of PPS by ion bombardment

Commercial-grade thin poly(p-phenylene sulphide) (PPS) foils; 2 mu m thick, have been bombarded with H-1(+) (380 keV), and with 0.61 MeV/amu He-4(+), C-12(2+), O-16(3+) S-32(3+), Br-79(9+) and I-127(14+) ions. The completely modified foils have been analyzed by Fourier transform infrared absorption spectroscopy (FTIR) and by ultraviolet-visible absorption spectroscopy (UV-VIS). The bond breaking and rearrangement processes were followed by using the FTIR results. The absorbance of bands related to C-S, S-S, C-H and most of the ring carbon bonds show an exponential decrease as a function of fluence. The absorption bands most sensitive to the ion bombardment are those assigned to C-S and S-S bonds. The C=C and C-H bonds are less sensitive and certain absorption band changes indicate carbon-carbon aliphatic and or aromatic conjugation, due to their increasing intensity as a function of the ion fluence. Damage cross sections have been extracted from the plots of IR absorbance versus fluence. The values of the damage cross sections obtained scale roughly with the square of dE/dx (independent of the nature of the chemical bond). The optical absorption coefficient has also been followed as a function of the ion fluence.