Tip-enhanced Raman Spectroscopy of Graphene

This paper presents an optical spectroscopy system engineered to overcome the diffraction limit, describing its building blocks and its application in the characterization of graphene. Based on a technique know as Tip-enhanced Raman Spectroscopy (TERS), the system is capable of obtaining images and spectral information from nanostructures smaller then the minimal length imposed by the diffraction limit of light through the use of optical nanoantennas designed to convert local evanescent radiation to propagating radiation and vice-versa. The system is described with focus on the optical components, including tip-light focus alignment, and on software to handle the massive amount of data generated in hyperspectral imaging. The system is utilized to extract rich information from a graphene nanofiake, with comments on important aspects to generate such spectral analysis.