Recent developments in Raman and IR spectroscopy of graphene materials

Raman spectroscopy is widely used to characterize graphene materials, principally because of its sensitivity to molecular structure details that encompass the extent of π-conjugation and the topology of the graphene edge [1]. Density functional theory calculations provide the interpretation of the observed Raman bands. This is done by assigning the nuclear displacements of the strong Raman transitions computed by DFT. In many circumstances, we have seen how this mixed experimental/theoretical approach can provide access to fine details in the molecular structure [2], [3], [4], [5], [6]. The information about the molecular structure of graphenes that this spectroscopic approach can gather is further enriched by complementing Raman spectroscopy with IR spectroscopy [7]. For instance, the direct evidence of the characteristic hole (i.e., one missing hexagon) in the center of a sizeable armchair-edged graphene molecule is immediately obtained by the assignment of the IR transitions in the CH out-of-plane bending region [4].