Graphite electronic structures

Partoens B, Peeters F (2006) From graphene to graphite electronic structure around the K point. Phys Rev B 74 075404... 

B. Pcirtoens, F.M. Peeters, From graphene to graphite Electronic structure aroimd the K point. Physical Review B - Condensed Matter and Materials Physics, 74 (7), 075404,2006. 

We will now discuss the electronic structure of single-shell carbon nanotubes in a progression of more sophisticated models. We shall begin with perhaps the simplest model for the electronic structure of the nanotubes a Hiickel model for a single graphite sheet with periodic boundary conditions analogous to those im-... 

As an example of a nanotube representative of the diameters experimentally found in abundance, we have calculated the electronic structure of the [9,2] nanotube, which has a diameter of 0.8 nm. Figure 8 depicts the valance band structure for the [9,2] nanotube. This band structure was calculated using an unoptimized nanotube structure generated from a conformal mapping of the graphite sheet with a 0.144 nm bond distance. We used 72 evenly-spaced points in the one-... 

Dravid et al. examined anisotropy in the electronic structures of CNTs from the viewpoint of momentum-transfer resolved EELS, in addition to the conventional TEM observation of CNTs, cross-seetional TEM and precise analysis by TED [5]. Comparison of the EEL spectra of CNTs with those of graphite shows lower jc peak than that of graphite in the low-loss region (plasmon loss), as shown in Fig. 7(a). It indicates a loss of valence electrons and a change in band gap due to the curved nature of the graphitic sheets. 

In order to examine the electronic structures of CNT it is necessary to first define the classification of structural configurations of CNT. The configuration of a CNT is constructed by enrolling a graphite sheet as illustrated in Fig. 1. That is. 

The optimised interlayer distance of a concentric bilayered CNT by density-functional theory treatment was calculated to be 3.39 A [23] compared with the experimental value of 3.4 A [24]. Modification of the electronic structure (especially metallic state) due to the inner tube has been examined for two kinds of models of concentric bilayered CNT, (5, 5)-(10, 10) and (9, 0)-(18, 0), in the framework of the Huckel-type treatment [25]. The stacked layer patterns considered are illustrated in Fig. 8. It has been predicted that metallic property would not change within this stacking mode due to symmetry reason, which is almost similar to the case in the interlayer interaction of two graphene sheets [26]. Moreover, in the three-dimensional graphite, the interlayer distance of which is 3.35 A [27], there is only a slight overlapping (0.03-0.04 eV) of the HO and the LU bands at the Fermi level of a sheet of graphite plane [28,29],... 

Attempts to elucidate the bonding have concentrated mainly on graphite-FeCla- This intercalate is especially suitable as a model compound, because the magnetic and Mossbauer properties of the iron nucleus constitute excellent probes for electronic structure and environment of the latter. 

In this contribution it is shown that local density functional (LDF) theory accurately predicts structural and electronic properties of metallic systems (such as W and its (001) surface) and covalently bonded systems (such as graphite and the ethylene and fluorine molecules). Furthermore, electron density related quantities such as the spin density compare excellently with experiment as illustrated for the di-phenyl-picryl-hydrazyl (DPPH) radical. Finally, the capabilities of this approach are demonstrated for the bonding of Cu and Ag on a Si(lll) surface as related to their catalytic activities. Thus, LDF theory provides a unified approach to the electronic structures of metals, covalendy bonded molecules, as well as semiconductor surfaces. 

Great promise exists in the use of graphitic carbons in the electrochemical synthesis of hydrogen peroxide [reaction (15.21)] and in the electrochemical reduction of carbon dioxide to various organic products. Considering the diversity in structures and surface forms of carbonaceous materials, it is difficult to formulate generalizations as to the influence of their chemical and electron structure on the kinetics and mechanism of electrochemical reactions occurring at carbon electrodes. 

This picture was found to be consistent with the comparison of Raman spectra and optical gap of a-C H films deposited by RFPECVD, with increasing self-bias [41], It was found that both, the band intensity ratio /d//g and the peak position (DQ increased upon increasing self-bias potential. At the same time, a decrease on the optical gap was observed. Within the cluster model for the electronic structure of amorphous carbon films, a decrease in the optical gap is expected for the increase of the sp -carbon clusters size. From this, one can admit that in a-C H films, the modifications mentioned earlier in the Raman spectra really correspond to an increase in the graphitic clusters size. 

Orientation Determination. While polarized edge studies, together with a known sample orientation, can provide information about the electronic structure of the absorber, one can also use polarized edges to probe ordered systems of unknown orientation. This sort of approach was used in a study of B adsorbed on graphite (26,27). In this case, the orientational dependence of an edge transition was used to calculate the degree of orientational purity of the graphite surface. 

Graphite possesses highly anisotropic layered crystal structure, which translates to a quasi-2D electronic structure with electronic bands dispersing linearly near Ep and forming point-like Fermi surfaces. Visible light induces... 

Noncovalent functionalization of graphene is important, as it does not affect the electronic structure and planarity of this 2D material. Stable aqueous dispersions of polymer-coated graphitic nanoplatelets can be prepared through an exfoliation and... 

C.A. Coulson, The electronic structure of the boundary atoms of a graphite layer, Fourth Conference on Carbon, Pergamon Press, University of Buffalo, Buffalo, NY, 1960, p. 215. 

In view of its electronic structure, carbon atoms in graphite are strongly bonded in planes, and only weak van der Waals forces hold the planes together. This leads... 

Band structure calculations of MgB2 show that the a states are unfilled and hence metallic, whereas for graphite a states are completely filled (An Pickett, 2001). It is sometimes useful to consider the geometrical and electronic structure of graphite when studying MOMs, because it summarizes the main features carbon-based, 2D and electrical conductivity given by nr-electrons. 

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