Carbon vapor plasma

Synthesis of Fullerenes. As mentioned above, the experiments leading to the first observation of the fullerenes involved the formation of carbon vapor plasma by... 

Mechanism of the Self-Assembly of Fullerenes, The spontaneous formation of fullerenes under the extreme high energetic conditions imposed by the carbon vapor plasma implies a considerable entropy loss which should be considered in... 

Graphite was tised as substrate for the deposition of carbon vapor. Prior to the tube and cone studies, this substrate was studied by us carefully by STM because it may exhibit anomalotis behavior w ith unusual periodic surface structures[9,10]. In particular, the cluster-substrate interaction w as investigated IJ. At low submonolayer coverages, small clusters and islands are observed. These tend to have linear struc-tures[12j. Much higher coverages are required for the synthesis of nanotubes and nanocones. In addition, the carbon vapor has to be very hot, typically >3000°C. We note that the production of nanotubes by arc discharge occurs also at an intense heat (of the plasma in the arc) of >3000°C. 

Consumable cathodes have been used in experiments in which carbon was one of the reactants. Carbon, vaporized from a graphite cathode, was used in the synthesis of cyanogen and hydrogen cyanide. Powdered carbon introduced in a gas stream or as a constituent of a gas has also been used as the source of carbon in a plasma flame. 

Thermal Plasma Production of Acetylene by Carbon Vapor Reaction with Hydrogen or Methane... 

When hydrocarbons are used as the stabilizing liquid in the plasma burner, even the coarser silica particles in the feed are reduced to SiO vapor, according to Kugler, Sins, and Silberger (453), who disclosed a burner design. A fluid convection electrode was described by Korman et al. (454). The so-called arc-silicas, which appear to be simply volatilized, are probably at least partly converted to SiO by the carbon vapor of the arc and then reoxidized. A series of products sold as Arc Silicas are described as 2-3 micron clusters of 15 nm particles (455). 

The Discovery of the Fullerenes. In experiments carried out at Rice University in 1985 associated with the presence of carbon in stars and space [Kroto HW, Heath JR, O Brien SC, Curl RF, Smalley RE (1985) Nature 318 162], the Ceo molecule was discovered. This species is one of the many carbon clusters which can be generated when a plasma of carbon vapor produced in the surface of graphite by laser irradiation is cooled by an inert gas jet. The detection of this type of carbon aggregate which appears to constitute a third allotropic and the first molecular form of carbon by mass spectroscopy is illustrated in Fig. 4.18. 

Aluminum is best detected quaUtatively by optical emission spectroscopy. SoHds can be vaporized direcdy in a d-c arc and solutions can be dried on a carbon electrode. Alternatively, aluminum can be detected by plasma emission spectroscopy using an inductively coupled argon plasma or a d-c plasma. Atomic absorption using an aluminum hoUow cathode lamp is also an unambiguous and sensitive quaUtative method for determining alurninum. 

The sudden expansion of the gases, as they are heated in the arc plasma, causes the formation of a high-speed arc jet so that the atomic hydrogen and the reactive carbon species are transported almost instantly to the deposition surface and the chances of hydrogen recombination and of vapor-phase reactions are minimized. 

Wong, W.W., Cochran, W.J., Klish, W.J., Smith, E.O.B., Lee, L.S. and Klein, P.D. 1988 In vivo isotope-fractionation factors and the measurement of deuterium- and oxygen-18-dilution spaces from plasma, urine, saliva, respiratory water vapor, and carbon dioxide. American Journal of Clinical Nutrition 47 1-6. 

At the end of last century, a near frictionless carbon (NFC) coating was reported, which is practically hydrogen contained DLC film grown on steel and sapphire substrates using a plasma enhanced chemical vapor deposition (PECVD) system [50]. By using a ball on a disk tribo-meter, a super low friction coefficient of 0.001-0.003 between the films coated on both the ball and the disk was achieved [50]. A mechanistic model was proposed that carbon atoms on the surface are partially di-hydrogenated, resulting in the chemical inertness of the surface. Consequently, adhesive interaction becomes weak and super low friction is achieved [22],... 

Popov, C., Zambov, L. M., Plass, M. R, and Kulisch, W., Optical, Electrical and Mechanical Properties of Nitrogen-rich Carbon Nitride Films Deposited by Inductively Coupled Plasma Chemical Vapor Deposition," Thin Solid Films, Vol. 377-378,2000, pp. 156-162. 

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