On depth profiling of polymers by argon ion sputtering

Organic polymers readily react after the impact of energetic ions as used in sputter depth profiling. The resulting chemical composition (elemental concentrations, structural features) is different from the original one. These alterations are observed after a short time exposure of polyethylene (PE) and poly(ethylene terephthalate) (PET). The XPS data of the C1s and the O1s regions changed dramatically. Electron spin resonance measurements support the assumption that radicals are involved in the reactions. The chemical surface composition of these polymers was changed by the ion bombardment in a way that it is virtually impossible to tell anything about the original structure. The depth profile is mostly an artefact.