An AFM study of the surface of a polymer film bombarded by low energy gaseous ions

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He, Dixon D.
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This research studies the radiation damage on polymeric materials caused by accelerated ions. Gaseous ions are accelerated to different energies between 10 keV and 50 keV at fluences up to 10$\sp{15}$ ions/cm$\sp2$ by 200 keV Whickham ion accelerator at room temperature. The 2 x 2 cm$\sp2$ polyimide Kapton films, with measured thickness of 62 micron, is bombarded by selected ions from an incident direction normal to target surface. The penetration depth of ions at this energy level is of a few microns which is much less than the thickness of the target, so the kinetic energy of the ion is completely deposited into the target to cause radiation damage. The radiation damage results on the target is analyzed by contact mode atomic force microscopy (AFM) performed in ambient condition. Different types of surface topographic features are observed on ion bombarded Kapton. The depth of damage is measured and compared with the calculated result from TRIM program which is based on the ZBL (Ziegler, Biersack and Littmark) theory of stopping power and range. The depth measurements and unique cross-section of the radiation-induced damage clearly support he proposed model for ion induced crater formation on a polymer surface.