Pressure-induced reversible transformation in single-wall carbon nanotube bundles studied by Raman spectroscopy

We report our high-pressure Raman studies on single-wall carbon nanotube bu ndles carried out up to 25.9 GPa. The intensity of the radial modes decreas es more drastically as compared to that of the tangential modes. The former could be followed up in pressure runs to 3 GPa. The most intriguing observ ation is the anomalous pressure behaviour of the 1594 cm(-1) tangential mod e between 10 and 16 GPa. This feature, as well as the pressure dependence o f intensity, peak position and linewidth, are reversible on decompression. The anomalous pressure dependence is argued to be associated with faceting of the tubes in the bundle, showing their remarkable resilience. (C) 2000 E lsevier Science B.V. All rights reserved.