G‐mode behaviour of closed ended single wall carbon nanotubes under pressure

Abstract We have performed high pressure Raman experiments on closed‐ended single wall carbon nanotubes using two different excitation wavelengths: 632.8 nm and 514 nm. We found that the shape of the G‐mode spectrum changes while changing the excitation wavelength at lower pressures, while it becomes similar at 3.5 GPa. In addition we record that the value of the transition pressure, associated with the structural transitions in the tubes, has also changed with changing the excitation wavelength even though we are examining tubes from the same produced sample. We attribute these results to the tubes having different electronic nature (metallic; semi‐conducting) and different diameters in resonance with each excitation wavelength. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)