Effect of chemical environment on high-pressure Raman response of single-walled carbon nanotubes

Abstract

The pressure-induced Raman peak shifts for single-walled carbon nanotubes (SWNTs) have been studied using different solvents as hydrostatic pressure-transmitting fluids (PTF). We suggest that the variation in the nanotube response to hydrostatic pressure with different PTF is evidence that the common solvents used are able to penetrate the interstitial spaces in the nanotube bundle. With hexane, we find the surprising result that the individual nanotubes appear unaffected by hydrostatic pressures (i.e. a flat Raman response) up to 0.7 GPa. Qualitatively similar results have been obtained with butanol. Following the approach of Amer et al. [M. S. Amer, M. S. El-Ashry and J. F. Maguire, J. Chem. Phys. 121 2752 (2004)], we speculate that this is due to the inability of SWNTs to adsorb some solvents onto their surface at low pressure.

Keywords:

• High pressure
• Raman spectroscopy
• Nanotubes
• Cohesive energy density
• Carbon
• Absorption

Acknowledgements

The authors thank James Elliott and Pascal Puech for useful discussions, Uschi Bangert and Alan Harvey for TEM. One of the authors (J.P.) also thanks the EPSRC for financial support.