平原 佳織

Electron energy-loss spectroscopy (EELS) is widely used to identify elemental compositions of materials studied by microscopy. We demonstrate that the sensitivity and spatial resolution of EELS can be extended to the single-atom limit. A chemical map for gadolinium (Gd) clearly reveals the distribution of Gd atoms inside a single chain of metallofullerene molecules (Gd@C ) generated within a single-wall carbon nanotube. This characterization technique thus provides the "eyes" to see and identify individual atoms in nanostructures. It is likely to find broad application in nanoscale science and technology research. 82

Two common methods of oxidation, gas-phase oxidation by heat treatment in oxygen gas and liquid-phase oxidation using nitric acid, were applied to single-wall carbon nanotubes (SWNT). The heat treatment in oxygen showed that thinner SWNTs burn more quickly. The nitric acid treatment showed that SWNTs are relatively inert to oxidation using acids. When the nitric acid treated samples were further oxidized by heat treatment in oxygen, selective oxidation of thinner SWNTs occurred. © 2000 Elsevier Science B.V.

Single-wall carbon nanotubes (SWNTs) were mass-produced by a newly developed DC arc plasma jet method for the evaporation of a metal-doped carbon anode. The production rate of the cottonlike soot was significantly higher than that by conventional DC arc discharge evaporation, and the highest yield was 1.24 g/min. Investigations by scanning electron microscopy, high-resolution transmission electron microscopy and Raman spectroscopy indicated that more than 50% of the cottonlike carbon soot was composed of fibrous bundles of SWNTs. Through analysis of the breathing modes in the Raman spectra of the cottonlike soot, the diameter of each SWNT was determined to range from 1.28 to 1.52 nm.