The blue shifts have occurred repeatedly for different batches of the same samples and was thus considered to be significant. The blue shift of E 1 2g indicates a reduction in the number of layers after functionalization, which is consistent with the AFM results . It also implies a compressive strain being generated due to the functionalization . The reduction in the number of layers are supposed to induce a red shift of the A1g mode, however here we observed a blue shift. Since a blue shift of A1g also indicates a compressive strain , it is suggested that the effect from compressive strain has dominated so that we observe a blue shift as a result. The functionalization has also caused the D and G peak intensity ratio to increase as shown in Figure