Interactions of ion beams with polymers: the physical picture

The implantation of energetic ions into a solid causes a significant transformation of the structure and properties of its surface layer. The movement of ions penetrating into the solid causes collisions with atoms and electrons of the molecules along the ion path. As a result of these collisions, the atoms and electrons of the ion-implanted material are shifted from their equilibrium positions, leading to atomic displacements and the excitation of vibrational modes. The vibrational energy is dissipated in the material by the propagation of phonons. The collision cascades produced by the ions implanted can be considered according to the theory of particle scattering using a binary collision model to give ion penetration depths, atomic vacancy, phonon, and scattered atom and electron distributions. Estimates of the distribution of radicals created under the surface in polymers can be obtained by examining the distribution of atomic vacancies together with the atom valencies.