Comparative study of the stopping power of graphite and diamond

The stopping cross section of graphite and diamond for hydrogen and helium projectiles in the energy range 20 less than or equal to E less than or equal to 80 keV/amu has been measured. It is found that in the case of graphite the stopping cross section for protons is up to 40% larger than that of diamond, while for He projectiles the difference is about one-half of that. The results are explained using the charge-state approach to stopping, that includes in an approximate manner the energy loss in charge-exchange processes and a simple model for the valence-electron excitations of the two allotropic forms of carbon.