Graphite fragments, carbon clusters

Large clusters of carbon atoms have been studied with ab initio calculations using basis sets of double-C quality. Planar, single-sheet graphite fragments with 6 - 54 atoms were investigated, as well as the spherical "Buckminsterfullerene ... 

From the two-dimensional, graphite-like clusters, the extension to three-dimensional structures is obvious. Symmetric structures developed in a similar fashion to the planar systems would grow in three dimensions with increasing N, and the number of atoms would increase faster. In this work clusters of T symmetry were studied, resembling a small fragment of a diamond structure. Only systems with saturated external bonds were considered. The number of carbon and hydrogen atoms in such a structure is given by... 

Particles of carbon black are very small, with diameters in the range 10-300 nm, and densities of about 1.8 Mgm-3. They consist of roughly spherical clusters of small fragments, each of which is similar to a small bit of graphite... 

The Ed distribution exhibits a desorption threshold for the carbon desorbed from the graphite matrix (in atomic form but also in C2 and C3 clusters) around 4.5 mJ/pulse. Therefore, in the Ed interval for the PAHs detection (cf Fig. 3), the underneath carbon matrix should not be destroyed. Supposing a similar structure for a soot matrix, one can achieve a smooth desorption process, without appearance of species artificially produced by the ejection of soot particles fragment during desorption. 

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