Electronic sputtering from HOPG: A study of angular dependence

The angular distribution of the sputtering yield from highly oriented pyrolytic graphite sample irradiated with a 130 MeV Ag beam is studied. The beam was incident perpendicular to the sample and the sputtered carbon was collected on Si catcher foils which were studied using a high resolution ERDA set up. An anisotropic distribution of sputtering is observed with a distribution C=Acos1.3Θ+Bexp(-(Θ-53)2/σ2) which shows that a peak lies at around 53 deg. on a distribution which otherwise is a over-cosine function. The maximum sputtering yield is observed at 53 deg., falling rapidly to almost zero at 90 deg., with an average sputter yield of 5.5 x 105 atoms/ion. It is suggested that this anisotropy may be due to the crystal structure and formation of a pressure pulse