High-pressure studies of carbon nanotubes

Abstract

Considering carbon nanotubes as a rolled-up graphene sheet, the basic properties of the Raman scattering of nanotubes can be predicted from the Raman of graphite. We expect increased pressure coefficients if the nanotubes are impermeable to the pressure medium and the same as graphite if they are filled; also if they collapse at high pressures. The literature is reviewed to see how well these predictions are borne out in practice. New experiments are reported, which confirm the crucial effects of the nature of the pressure-transmitting medium (solvent), which is unexpected, and the resonances with the Raman excitation energy (expected). Key open questions include the mechanism of the solvent effect and the influence of bundling.

Keywords:

• carbon nanotubes
• Raman scattering
• diamond anvil cell
• pressure medium

Acknowledgements

A.J.G. thanks the Al Tajir Trust for financial support.