Raman spectra of plasma-thinned few-layer graphene sheets with different thicknesses. The three spectra were collected from three different spots respectively. The positions of the three spots are labeled in the inset optical image of a sample subjected to 5 s of CF4 plasma treatment. Scale bar, 5 μm.
Shen et al. Nanoscale Research Letters 2012 7:268 doi:10.1186/1556-276X-7-268