Basal plane of graphite

Fig. XVII-18. Contours of constant adsorption energy for a krypton atom over the basal plane of graphite. The carbon atoms are at the centers of the dotted triangular regions. The rhombuses show the unit cells for the graphite lattice and for the commensurate adatom lattice. (From Ref. 8. Reprinted with permission from American Chemical Society, copyright 1993.)...

A distinct answer has been found, however, with respect to the influence of crystallographic orientation of pyrolytic graphite on the rates of various reactions. It could be shown that the rate of cathodic oxygen reduction at the basal plane of graphite is much lower than at surfaces with edge orientation (Morcos and Yeager, 1970). To the contrary, the rates of simple redox reactions hardly depend on face orientation. 

The basal plane of graphite (or HOPG) is essentially free from surface oxygen functionalities. This is manifested by almost flat, featureless... 

Single planar sheet of sp -bonded carbon atoms corresponds to one hexagonal basal plane of graphite and is termed graphene. Recently, a successful attempt to isolate such a graphene layer has been reported [3], and apparently, it becomes possible to produce... 

Figure 9.13 Adsorption of nitrogen to a single basal plane of graphite at a temperature of 46.2 K as determined by ellipsometry. Plotted is the change in the ellipsometric angle A versus pressure. The subsequent adsorption of at least four layers at defined pressures can clearly be distinguished. Redrawn from Ref. [389].

Figure 4.3. Phase diagram for physisorbed rare gas atoms or molecules on uniform solid surfaces such as the basal plane of graphite (after Suzanne and Gay, 1996).

The highly distinctive form of a Type VI isotherm is due to a stepwise layer-by-layer adsorption process. Such isotherms are given by the adsorption of simple non-polar molecules (e.g. argon, krypton and xenon) on uniform surfaces (e.g. the basal plane of graphite). The steps become less sharp as the temperature is increased. The vertical risers can be regarded as the adsorbed layer boundaries and the centres of the treads (inflection points) as the layer capacities. When present, sub-steps are associated with two-dimensional phase changes in the monolayer. Useful information concerning the surface uniformity and adsorbate structure can be obtained from the relative layer capacities and the presence of sub-steps. 

This moleeule interacts in a very stable way in aqueous solution through the aromatie rings with the basal plane of graphite via rr-staeking with the sidewalls of SWCNTs. The succinimidyl residues are highly reactive to nucleophilic substitution by primary and seconday amines of proteins or other moleeules. SWCNTs were incubated in a pyrenebutanoie aeid, sueeinimidyl ester solution (6 mM in DMF or 1 mM in methanol) for 1 h at room temperature followed by careful rinsing in pure DMF or methanol. The proteins were then immobilized by... 

In fig. 1.3 two examples of an AFM picture are given. Figure 1.3a is a typical AFM image. It shows hexagonal symmetry for the basal plane of graphite measured in the contact mode K In this case the apparent symmetry does not correspond to the presumed trigonal symmetry, because AFM does not always show real atomic scale resolution. Real atomic scale resolution that showed... 

Figure 8. Center-of-mass trajectories obtained from a simulation of a patch of nitrogen molecules adsorbed on the basal plane of graphite. (Carbon atoms are shown by the small dots.) In part (a) for T=36.9 K, the molecules are commensurate with theVSxVS lattice and vibrate around the site centers except at the edges of the patch. In part (b), 7M4.0 K and the patch has mehed to a 2D fluid that is characterized by chaotic trajectories in the him. (At longer simulation times, the molecules appear to fill the surfece as a 2D gas.) From Ref. [38], Mol. Phys. 55 (1985) 999-1016.

Phase diagrams for strongly polar molecules in adsorbed films are still in the process of development even for the films on the basal plane of graphite [35]. These systems are made more complex because of the interplay of dipolar forces and molecular shape in determining preferred orientations relative to the surface and to neighboring molecules. A simulation of Stockmayer molecules (Lennard-Jones atoms with ideal dipoles attached) adsorbed on a featureless slit pore at low temperature [46] has shown that the dipoles tend to lie parallel to the surface in... 

F. Y. Hansen, L. W. Bruch and H. Taub, Mechanism of Melting in Submonolayer Films of Nitrogen Molecules Adsorbed on the Basal Plane of Graphite, Phys. Rev. B 52 (1995) 8515-8527 Y. P. Joshi and D. J. Tildesley, A Simulation Study of the Melting of Patches of N2 Adsorbed on Graphite, Mol. Phys. 55(1985) 999-1016. 

---