Evolution of clusters in energetic heavy ion bombarded amorphous   graphite-III: Photo-emission and velocity analysis of sputtered carbon   clusters
  Diagnostics of the carbon atoms, ions, and clusters sputtered from a graphite surface under 10 keV Xe ion bombardments reveals the presence of neutral carbon clusters and positively charged species in the photo-emission spectra. The observed absence of the positively charged clusters in the mass spectra by a velocity analyzer is supplemented by the presence of the negatively charged monatomic, diatomic, triatomic and quatratomic clusters.. The velocity spectra are dominated by the negative C1, C2, C3 and C4. The latter two are observed having much reduced peak intensities . These results may help us to understand the contribution of neutral and charged species in the heavy-ion sputtering of graphite and the energetics of soot formation. Xe is chosen being the heaviest noble gas ion irradiating at not too high energy i.e 10 keV. 
A. Qayyum, M. N. Akhtar, T. Riffat, and Shoaib Ahmad
cond-mat.mes-hall