Raman spectroscopy of graphene in different dielectric solvents

We have studied the effect of different dielectric environments on the properties of graphene by Raman spectroscopy. Graphene was produced by micromechanical exfoliation of graphite and deposited on a silicon substrate covered with 300 nm of silicon oxide (Si/SiO2). Graphene was immersed in water, ethanol and chloroform, which have a dielectric constant of 80, 30 and 4.8, at room temperature, respectively. We show that water immersion reduces the effect of charged impurities. Ethanol produces strong changes in the Raman spectrum. Graphene rolls and wrinkles once immersed in ethanol, as observed by optical microscope. Finally, chloroform produces a strong p-doping as observed by the up-shift of the G and 2D peaks. This shows that Raman spectroscopy is able to characterize the electrostatic environment of graphene (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)