User science highlight: Graphene sheet observed with optical method
Sample confocal microscope images of reflection from the single layer of graphene oxide at different laser wavelengths.
A simple approach is needed to identify nanometer-scale layered materials such as graphene, clays, metal dichalcogenides, and self-assembled monolayers. A collaborative CNM user project has developed a simple optical identification method employing standard confocal microscopy.
High contrast is obtained by depositing the materials on a substrate consisting of a thin dielectric layer on silicon. By varying the wavelength of light used in the microscope, effective refractive indices and absorption coefficients can be determined. An example has been carried out for graphene, graphene oxide, and reduced graphene oxide. Single-atomic layers of graphite – graphene – attract widespread attention because of their unique electronic and mechanical properties. These measurements provide important physical information that complement electrical and chemical characterization techniques. The approach should be readily extendable to other nanometer-scale layered materials.
I. Jung, M. Pelton, R. Piner, D. A. Dikin, S. Stankovich, S. Watcharotone, M. Hausner, and R. S. Ruoff. "Simple Approach for High-Contrast Optical Imaging and Characterization of Graphene-Based Sheets," Nano Lett., 7, 3569-3575 (2007).