Damage of graphite surfaces resulting from ion bombardment, studied by means of electron microscopy. Raman- and x-ray photoelectron spectroscopy

The radiation damage of the crystal lattice under ion inplantation displays a distinct depth profile with a maximum located at a depth slightly less than the projected ion range. Annealed pyrolytic graphite samples in a basal plane orientation were bombarded with helium ions in an energy range of 1 to 4MeV in order to suppress sputtering. The resultant build up of the lattice stress was followed by the scanning electron microscopy, Raman and x-ray photoelectron spectroscopy. In spite of the negligible number of lattice defects produced in the first few surface monolayers by the primary knock ons, a large lattice stress is induced there as has been shown by the vanishing of the photoelectron channelling. The stress anneals only above 15000C. (Auth.)