Surface modifications of sapphire single crystals and PET polymer induced by swift heavy ions

Surface changes in sapphire single crystals with four different orientation s produced by irradiation with Kr, Xe and Bi swift ions and in polyethelene therephtalate thin films produced by Xe ions have been studied by means of Atomic Force Microscopy. It was observed that individual surface defects wi th density corresponding to the ion fluence have been detected for sapphire samples only for Bi ions with energy higher than 269 MeV. These defects we re found to have complicated structure - a hillock surrounded by a border r ing or a hillock with cavity on the top, the type of structure depending on irradiation energy. The surface track shape in polymer was found to depend on polymer treatment: small cavity just after the irradiation, bigger cavi ty after low-temperature annealing and the hillock after high-temperature a nnealing. It was shown that annealing of the polymer allows to visualise di fferent areas around the track axis. A possible mechanism of such behaviour (amorphisation and crystallisation) was discussed.