The defect structure of multi-walled carbon nanotubes was studied using transmission electron microscopy and Raman spectroscopy, with particular attention to the shape and intensity of the defect band, D, and its overtone, D*. Electron microscopic results demonstrated that multi-walled nanotubes typically had multiple bends. The associated short- and long-range disorder influenced the Raman spectrum of the nanotubes. The presence of several defect species, differing in scattering probability, resulted in a stochastic relationship between the intensities of the D*- and D-bands. This relationship was qualitatively interpreted in terms of general mechanisms of elastic/inelastic interactions of π-electrons with phonons and defects.

Defect Structure of Multiwalled Carbon Nanotubes Studied by Raman Spectroscopy. E.M.Baitinger, N.A.Vekesser, I.N.Kovalev, Y.I.Ryabkov, V.V.Viktorov: Inorganic Materials, 2011, 47[5], 471-4