| Popis: |
In the x-ray diffraction of carbonaceous materials, there is no logical reason to assume an interrelation between the intensity of the (002) peak, reflecting intermolecular “stacking” order of aromatic planes, and the fractional aromaticity fa measured by carbon nuclear magnetic resonance. Approaches to the calculation of a diffraction-based aromaticity f002 by comparing the intensity of the (002) peak to that of the γ-band at 450 pm, reflecting intermolecular order of saturated chain hydrocarbons, are fundamentally flawed. The use of diffraction linewidth data for peaks near 210 pm (“(100)”) and near 120 pm (“(110)”) to infer an aromatic diameter has difficulties in systems containing hydroaromatic molecules (e.g., tetralin) because the naphthenic moiety contributes to diffraction peaks in the 210 and 120 pm regions. |
