Radiation damage and Raman vibrational modes of single-walled carbon nanotubes

We report on the behavior of Raman scattering for the radial and tangential vibrational modes of single-walled carbon nanotubes (CNT) with different absorption doses of high-energy electron irradiation (Ee = 1.8 MeV). We find that the atomic displacement of carbon from the CNT walls leads to the decrease of their diameter. In the case of the tangential optical vibrations the translational symmetry of CNT breaks down because of the radiation defects. Thus, new vibrational modes both for the armchair and zigzag CNT appear. Substantial changes in the intensities and broadening are observed for the high-frequency Raman bands with a 1.0 MGy absorption dose.