Carbon amorphous, electron

Other types of carbon (amorphous or transitional forms with turbostratic structure) consist of fragments of graphitelike regions cross-linked to a three-dimensional polymer by carbon chains. Unlike graphite, the transitional forms are organic semiconductors with electrical properties determined by delocalized rr-electrons. 

XPS and FT-IR were used to characterize the modified CNT surfaces. The combined results provided quantitative information on the chemical composition and structure of CNTs. For XPS, when an X-ray beam is directed at the SWNT surface, the energy of the X-ray photon is absorbed by a carbon core electron. The core electron escapes from the atom if the photon energy is sufficiently large. Since CNTs are made up of a hexagonal lattice of carbon atoms analogous to die atomic planes of graphite, one can easily obtain the main peak at 285 eV from Cls. However, die raw material usually contains amorphous carbon and various... 

This chapter is divided into ten sections (1) introduction (2) allotropic forms of carbon (3) processing routes of carbon (4) structure of some novel phases of carbon (5) electrical and electronic properties of conducting carbon (6) electronic structure to explain electrical and optical properties (here we introduce the mechanism of conduction, interaction between carriers, localization, and the role of hydrogen concentration and dopant in the conductivity of carbon films) (7) optical properties (8) spectroscopic study (IR, Raman) (9) defect study in amorphous carbon and (10) applications and conclusions. We wish to give a view of novel forms of carbon and to analyze their special characteristics rather than review the well-known earlier work. The interrelationship among the different sections gives a complete picture of amorphous carbon and its importance at present from various aspects. 

MWCNT synthesized by catalytic decomposition of hydrocarbon does not contain nanoparticle nor amorphous carbon and hence this method is suitable for mass production. The shape of MWCNT thus produced, however, is not straight more often than that synthesized by arc-discharge method. This differenee could be aseribed to the strueture without pentagons nor heptagons in graphene sheet of the MWCNT synthesized by the catalytic decomposition of hydrocarbon, which would affect its electric conductivity and electron emission. 

Fig. 3. High-resolution electron micrograph (HREM) of oxidised CNT tips. Note the amorphous carbon residue inside the lower nanotube (marked with an arrow).

Weiler, M., Lang, K., Li, E., and Robertson, J., "Deposition of Tetrahedral Hydrogenated Amorphous Carbon Using a Novel Electron Cyclotron Wave Resonance Reactor, Appl. Phys. Lett., Vol. 72,1998,pp. 1314-1316. 

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. 

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