Explanation of Raman spectrum

1. Raman spectroscopy is used to check the presence of a D peak in graphene samples. If a D peak is present, then this can indicate defects in the sample, such as cracks or flaking.
2. The ratio of the heights of the 2D peak and the G peak indicate the number of graphene layers.
   2D>G : Single-layer
   2D=G : Double layer
   2D<G : more than triple layer
3. 3 measurements for every sample are taken and presented on the same graph.