Difference in stopping cross section factor for 4He ions between polycrystalline diamond and glassy carbon

In order to study the allotropic effect on a stopping cross section of carbon, the difference in stopping cross section factors [ε] between polycrystalline diamond and glassy carbon (GC) has been estimated for 4He ions at the incident energies of 1.4–4.0 MeV by backscattering spectrometry. Thin Ag films (∼90 nm) were deposited onto the carbon targets to monitor the backscattering yields of Ag during the measurements. The relative stopping cross section factors [ε]GC/[ε]diamond can be determined from the backscattering C yields normalized by the Ag yields. The stopping cross section factors of glassy carbon [ε]GC are found to be higher by 4–5% than those of polycrystalline diamond [ε]diamond for all incident energies examined.