Raman spectra of different ribbons: a monolayer, a misoriented bilayer, and a turbostratic multilayer with their corresponding relative extinction. A misoriented bilayer has a similar Raman spectrum than a monolayer with a twice intensity. The multilayer corresponds to eight graphene sheets that are all disoriented with respect to each other. Therefore, the single Lorentzian shape of the 2D band cannot be used as a proof to assert the monolayer character of a FLG sample.
Tiberj et al. Nanoscale Research Letters 2011 6:478 doi:10.1186/1556-276X-6-478