Raman study of ion-induced defects in N-layer graphene.

Raman scattering is used to study the effect of low energy (90 eV) Ar(+) ion bombardment in graphene samples as a function of the number of layers N. The evolution of the intensity ratio between the G band (1585 cm(-1)) and the disorder-induced D band (1345 cm(-1)) with ion fluence is determined for mono-, bi-, tri- and ∼50-layer graphene samples, providing a spectroscopy-based method to study the penetration of these low energy Ar(+) ions in AB Bernal stacked graphite, and how they affect the graphene sheets. The results clearly depend on the number of layers. We also analyze the evolution of the overall integrated Raman intensity and the integrated intensity for disorder-induced versus Raman-allowed peaks.