ION IRRADIATION OF POLYMERS

The keV-MeV ion irradiation of polymers produces deep changes in their physical and chemical properties associated with the breaking and rearrangement of original bonds. The modification of chain structure occurs within a well defined ion fluence range which depends on the ion linear energy transfer as well as on the target parameters. At low ion fluences (approximately 10(14) ions/cm2) crosslinks between chains and chain-scissions are detected with a chemical yield in the range 0.05-0.3, depending on the ion mass. With increasing ion fluence (10(15) ions/cm2) the original polymer structure is heavily modified and the irradiated films exhibit properties close to those of hydrogenated amorphous carbon. At very high fluences (approximately 10(16) ions/cm2) graphitization of the material occurs.