Alexandre Merlen, équipe Nanostructuration IM2NP, co-auteur : "Raman Spectroscopy Characterization of Carbon Materials : From Graphene to All-carbon Heterostructures"

A large variety of carbon nanoforms are currently produced and studied worldwide, such as nanotubes, fullerenes, nano-onions, nanocones, stacked nanocones, scrolled graphene, nanofibers, nanowalls, nanosheets and nanoplates. Graphene is their initial building block, and by applying a transformation, such as stacking, cutting, circularly wrapping, scrolling, coiling and/or screwing, the other forms can be obtained. In 2012, a nomenclature to classify all these sp2 carbon nanoforms was proposed by Suarez-Martinez et al. To help researchers in their bibliographic researches, they proposed to classify all the known forms into three main families: molecular forms (0D), cylindrical nanoforms (1D), and layered nanoforms (2D). Raman spectroscopy is a non-destructive analysis technique which is particularly well suited to characterization of carbon (nano)materials. It is highly sensitive to carbon–carbon bonds and is able to provide a wealth of information about their structure. If one wants to understand the Raman spectra of the various carbon nanoforms as well as all-carbon heterostructures, one has to understand first the Raman spectrum of graphene and diamond as they represent the pure sp2 and pure sp3 allotrope cases. In this review chapter, we briefly present the basic principle of Raman spectroscopy. We then discuss the Raman signature of carbon materials in general. The last part is focused on Raman spectroscopy applied to carbon heterostructures. Rather than present an exhaustive list of Raman signatures of all carbon hybrids, we have deliberately chosen to focus on specific heterostructures as an illustration of the general interest of this technique.