Identifying chemical functionalization on individual carbon nanotubes and graphene by local vibrational fingerprinting.

Chemical functionalization of carbon nanotubes (CNTs) and graphene allows for fine-tuning their physical and chemical properties to realize fascinating new fundamental phenomena as well as exotic applications. A primary challenge in such endeavors is the need to identify the chemical nature of attached functionalities at a single-nano-object level in a spatially resolved manner. Here we report the vibrational fingerprinting of functional groups that are attached to individual CNTs and graphene flakes. In order to achieve this, we decorate noncovalently functionalized CNTs and graphene with nanoparticles, which leads to the appearance of Raman peaks that can be correlated with the vibrational modes characteristic of the functional groups with diffraction-limited spatial resolution. The presented strategy is generic enough to be extended to other chemical modification routes on a range of nanostructures and hence will allow for rapid characterization of chemical modification of individual (semi)conducting nanostructures.