Raman spectroscopy of holey nanographene C216

We report a detailed investigation by Raman spectroscopy of the holey nanographene C216, a hexagon-shaped disk with armchair edges (1.4 nm long), from which the central aromatic ring is missing. Density functional theory (DFT) calculations allow to assign the main features of the Raman spectra that have been recorded with several excitation wavelengths. In the Raman spectra, we observe signatures of the hole in the structure, several G and D modes, as well as their overtones and combinations—up to third order.