STM AND AFM OBSERVATIONS OF DAMAGE PRODUCED BY SWIFT NE AND KR IONS IN GRAPHITE

Radiation damage of highly oriented pyrolitic graphite (HOPG) samples have been investigated following irradiation with 215 MeV Ne and 209 M eV Kr ions, available at U-400 cyclotron, Dubna. A freshly cleaved HOP G surface was irradiated perpendicularly to the sample surface (c plan e). A low ion irradiation dose was used (10(12) ions/cm(2)) in order t o avoid damage overlap. Scanning tunneling microscopy (STM) and atomic force microscopy (AFM) are useful methods allowing direct observation of surface defects. The observations were made after irradiation with out any further sample preparation. The experimental results are compa red to computer simulations (TRIM code) and primary knocked-on atomic spectrum calculations (LET code). Clear distinction can be made betwee n surface features attributed to nuclear stopping effects and defects owing to electronic stopping mechanisms.