The controlled introduction of defects into aligned multi-walled C nanotubes was carried out via time-dependent plasma etching. Subsequent morphological changes in the nanotubes were then characterized by using Raman and X-ray photo-electron spectroscopy. The induction of defects by functionalization was thereby confirmed. It was found that the introduction of defects along the nanotube body affected all of the Raman vibrational modes. A systematic analysis of the relationship between the various modes led to the suggestion that no single peak could be used as an accurate standard for estimating the defect content in a nanotube.

Spectral Fingerprinting of Structural Defects in Plasma-Treated Carbon Nanotubes. N.Chakrapani, S.Curran, B.Wei, P.M.Ajayan, A.Carrillo, R.S.Kane: Journal of Materials Research, 2003, 18[10], 2515-21