Figure 1

(a) TEM of suspended graphene. The grid is also visible in optical microscopy. (b) High-resolution image of a folded edge of a single layer and (c) a wrinkle within the layer. (d) Folded edge of a two layer, and (e) internal foldings of the two layer. The amorphous contrast on the sheets is most likely due to hydrocarbon adsorbates on the samples that were cracked by the electron beam. (f) Electron diffraction pattern for close to normal incidence from single layer and (g) from two layers. Weak diffraction peaks from the supporting metal structure are also present. (h) Intensity profile plot along the line indicated by the arrows in (f),(g). The relative intensities of the spots in the two layer are consistent only with $A\mathrm{\text{−}}B$ (and not $A\mathrm{\text{−}}A$) stacking. Scale bars: (a) 500 nm; (b–e) 2 nm.Reuse & Permissions

Figure 2

(a) Comparison of Raman spectra at 514 nm for bulk graphite and graphene. They are scaled to have similar height of the $2D$ peak at $\sim 2700{\mathrm{cm}}^{-1}$. (b) Evolution of the spectra at 514 nm with the number of layers. (c) Evolution of the Raman spectra at 633 nm with the number of layers. (d) Comparison of the $D$ band at 514 nm at the edge of bulk graphite and single layer graphene. The fit of the $D_1$ and $D_2$ components of the $D$ band of bulk graphite is shown. (e) The four components of the $2D$ band in 2 layer graphene at 514 and 633 nm.Reuse & Permissions

Figure 3

DR for the 2D peak in (a) single layer and (b) bilayer.Reuse & Permissions