Figure 4.

Plot of the normalized integrated intensities of the G and 2D band against the relative extinction for several mono- and bilayer graphene. The G and 2D band integrated intensities are normalized with the integrated intensities of an HOPG reference sample. Theoretical values of the relative extinction are indicated by two vertical dashed lines. A correlation exists between the G band intensity and the relative extinction. Two cloud of points can be easily distinguished between mono- and bilayers thanks to the relative extinction. The scattering of the G band intensity is too large to use it as an absolute thickness measurement. The 2D band scattering is even higher especially for bilayer. 2D band of AB bilayer is as intense as monolayers whereas misoriented bilayers are twice intense than a monolayer.