Plasmons as the primary mechanism of ion-induced modifications in polymers

The phenomena that lead to modifications of polyimide, polycarbonate and po lyparaphenylene irradiated by an ion beam in the 100keV energy range are st udied. A model of energy transfer based on plasmon-like collective effects occurring during the physical stage of the ion-polymer interaction, previou sly implemented for poly(methyl methacrylate) and cellulosic derivatives, i s extended to these polymers. In the framework of this model, we carry out quantum-chemical calculations of the valence-band density of electronic sta tes. The resulting theoretical spectrum is then compared with the experimen tal plasmon line obtained by electron-energy-loss spectrometry. This approa ch sheds light on the selective bond cleavages induced by the energy transf er at the primary physical step of the ion-polymer interaction.