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The Raman shifts as functions of pressure were measured for the radial breathing mode and tangential modes in carbon nanoropes containing ͑10,10͒ and ͑17,0͒ single-walled tubes. An abrupt decrease in the rate of change of the Raman shift with pressure for the tangential modes, and the disappearance of the radial breathing mode, were observed at approximately 1.7 GPa. These changes in the Raman spectrum result from a structural phase transition as the nanoropes are compressed. Theoretical calculations using the empirical force method confirm this transition, as indicated by a calculated discontinuity in the lattice constants and unit cell volume at 1.7 GPa.

Uniform and small-diameter single-walled carbon nanotubes (SWNTs) have been produced using identical molecular nanoclusters containing Fe and Mo atoms with a defined molecular formula and a specific structure as catalysts in a chemical vapor deposition method. The average diameter of the SWNTs produced in these experiments is 1.0 nm with a standard deviation for the diameter distribution of 17%. The diameters of SWNTs were obtained by atomic force microscopy and Raman spectroscopy.

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