Abundance of encapsulated C-60 in single-wall carbon nanotubes

Spherical objects (presumably C-60 molecules) have been observed inside sim ilar to 14 Angstrom diameter single-wall carbon nanotubes. We applied acid etching to access the interior of the tubes, and leaching in toluene to dis solve liberated C-60. Quantitative UV-Vis of the 335 nm C-60 transition est ablishes beyond doubt that these are indeed C-60, and that their relative a bundance in a macroscopic sample can be as high as 5.4% (expressed as the f illed fraction of total tube length). Variations in abundance with growth a nd processing conditions provide clues as to how they form. (C) 1999 Elsevi er Science B.V. All rights reserved.