Carbon cluster diagnostics-I: Direct Recoil Spectroscopy (DRS) of Ar+   and Kr+ bombarded graphite
  Measurements of the energy spectra of multiply charged positive and negative carbon ions recoiling from graphite surface under 100 and 150 keV argon and krypton ion bombardment are presented. With the energy spectrometer set at recoil angle of 79.5 degrees, direct recoil (DR) peaks have been observed with singly as well as multiply charged carbon ions , where n = 1 to 6. These monatomic and cluster ions have been observed recoiling with the characteristic recoil energy E(DR) . We have observed sharp DR peaks. A collimated projectile beam with small divergence is supplemented with a similar collimation before the energy analyzer to reduce the background of sputtered ions due to scattered projectiles. 
Shoaib Ahmad, M.N. Akhtar, A. Qayyum, B. Ahmad, K. Bahar, W. Arshed
physics.ins-det