ИСТИНА

Raman scattering spectrometry (RSS) is a powerful method to study the structure of the carbon nanotubes (CNTs). Single wall CNTs (SWNTs) are characterized by three major lines, corresponding to G (graphite)-band, D (disordered)-band and, specific for SWNTs, RBM (radial breathing mode)-band. The latter disappear in the Raman spectrum of the multiwall CNTs (MWNTs), however the ratio of intensities of the first two, D and G, gives a useful information about defects in the CNTs. The structural properties of the MWNTs are of importance because of large-scale investigations of possible applications in composites for new functional materials. In the report, we make a comparison of Raman spectra for a variety of MWNTs, produced in the different regimes of a number of techniques: arc discharge deposition, glowing discharge enhanced deposition, pyrolitic gas depositions. A common feature in the Raman spectra of investigated MWNTs is the reversed ration of overlapping G+ (TO)-mode to G- (LO)-mode, compared with that for SWNTs. The intensity ratio G+/G- is larger than unity for SWNTs, while it is smaller than the unity for MWNTs. We show that the aligned CNTs (ACNTs), produced in the mixed flow of vapours of ferrocene and cyclohexane, have the least D/G ratio, compared with other type of MWNTs. Similar observation was made from the Raman spectra for polymer composites with vertically and horizontally aligned MWNTs. deposition.