Multishell fullerene

In general, the photoabsorption cross section of individual and multishell fullerenes reproduce the behaviour of the interstellar extinction curve in the near UV. The theoretical spectra show a prominent absorption band around 5.7 eV which fits well... 

Figure 6.25. Proposed scheme for the formation of the multishell fullerene C6o C24o- Reproduced from Mordkovich, V. Z. Shiratori, Y Hiraoka, H. Takeuchi, Y. Synthesis of Multishell Fullerenes by Laser Vaporization of Composite Carbon Targets, found onhne at http //www.ioffe.rssi.ru/joumals/ ftt/2002/04/p581-584.pdf.

Currently, there are few reports on the preparation of carbon onions and nanoparticles by means of chemical vapor deposition. It is obvious that this method just exceptionally suits the production of multishell fullerenes. 

It has already been mentioned in Section 2.3.5 that a rational synthesis of even the simplest fuUerene makes high demands on the preparation of a suitable precursor, which has to be closed to the carbon cage in a subsequent pyrolytic reaction. This problem becomes all the more salient in attempts on designing a strategy for the rational synthesis of multishell fullerenes it is not only the curvature of the carbon skeleton that must be considered here, but also the supramolecular pattern of concentric fullerenes of suitable sizes. Hence, for the time being, a directed synthesis of these multilayered species has not yet succeeded. 

The first carbon onions were synthesized in arc discharge experiments by lijima. It was demonstrated that the condensation of carbon vapor results in the formation of not only single-shell fullerene molecules but also of multishell fullerenes (i.e., carbon onions). It was proposed that quasi-spherical spiral-like particles could be intermediates for the formation of carbon onions via condensation of carbon vapor. - The close value of the diameter of the innermost shells of these carbon onions to the diameter of the Cgo fullerene molecule suggested the idea that another possible candidate for growth centers for carbon onions can be fullerenes themselves. ... 

Interestingly, a fullerene structure may serve as a nucleation site for additional layers of graphite en route toward multishell fullerenes (Figure 6.31). These are denoted as C6o C24o where the symbol represents the encapsulated species. There are even triple-layered structures such as Cgo C24o Though... 

Yannouleas, C., Bogachek, E. N. and Landman, U., Collective excitations of multishell carbon microstmctures multishell fullerenes and coaxial nanotubes. Physical Review B, 53 (15), 1996, 10225-10236. 

Abstract We review the potential contribution of single fullerenes and buckyonions to interstellar extinction. Photoabsorption spectra of these molecules are compared with some of the most relevant features of interstellar extinction, the UV bump, the far UV rise and the diffuse interstellar bands. According to semiempirical models, photoabsorption by fullerenes (single and multishell) could explain the shape, width and peak energy of the most prominent feature of the interstellar absorption, the UV bump at 2,175 A. Other weaker transitions are predicted in the optical and near-infrared providing a potential explanation for diffuse interstellar bands. In particular, several fullerenes could contribute to the well known strong DIB at 4,430 A comparing cross sections and available data for this DIB and the UV bump we estimate a density of fullerenes in the diffuse interstellar medium of 0.1-0.2 ppm. These molecules could then be a major reservoir for interstellar carbon. 

Noncovalent Interactions Between Graphene Sheets in Multishell (Hyper)Fullerenes. 

Grimme, S., Miick-Lichtenfeld, C, and Antony, J. (2007) Noncovalent interactions between graphene sheets and in multishell (hyper)fullerenes. /. Phys. Chem. A, 111, 11199-11207. 

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