The char the researchers used for experiments was derived from cellulose and the Raman spectra of char produced at different temperature were given in Fig. of their article . By means of the deconvolution of these spectra, the researchers concluded that experiments were consistent with the "growth of PAH clusters, loss of oxygen, and development of non-hexagonal ring systems as pyrolysis temperature increased". As previously told, Smith and coworkers performed simulations to understand the role of defect and used the experimental spectra of the abovementioned compounds to validate the presence of Raman active vibrations in char.