ION IRRADIATION INDUCED EFFECTS IN POLYAMIDOIMIDE

The interaction between ion beam and polyamidoimide (PAI) is studied by means of low-temperature infrared spectroscopy. 200 keV Ar+ and 250 keV He+ beams with fluences ranging from 10(13) ions cm-2 to 5 x 10(16) ions cm-2 are found to induce atomic bond breaks leading to absorption bands at 2344, 2261, and 2125 cm-1 corresponding respectively to CO2, C = N = N and C = N-R vibrations. Shrinkage of the polymer along with a drastic decrease of the resistivity during Ar+ and He+ irradiation are observed. Speculations on the respective role of electronic processes and atomic collisions in the evolution of the polymer are made. No evidence of PAI modification through knock-on mechanism for fluences lower than 5 x 10(15) ions cm-2 is noticed. In fact, our results would suggest a predominant role of the electronic processes for the low fluences (up to 5 x 10(15) ions cm-2), whereas a degradation mechanism based on atomic collisions is more likely to take place for higher fluences. A theoretical mechanism of reactions based upon our Fourier transform infrared (FTIR) and secondary ion mass spectroscopies (SIMS) results, describing the chemical changes occurring in the PAI, is presented and briefly discussed.