Correlations of RBM, G line, and D line frequencies of individual SWCNTs grown from carbon:nickel nanocomposite templates

Carbon:nickel nanocomposite templates were used for CVD growth of separated, individual single-walled carbon nanotubes (SWCNTs) free of solvents or surfactants. The as-grown carbon nanotubes were characterized by laser-energy dependent Raman spectroscopy and atomic force microscopy. Raman spectra showing a single radial breathing mode (RBM) line were analyzed with respect to correlations of RBM, G+ line and D line frequencies for SWCNT diameters covering the range of 0.8 nm to 1.6 nm. Opposite line shifts were found for RBM and G+ lines of the individual SWCNTs. However, the line shifts of the G+ line are smaller than the standard deviation of the G+ position for SWCNTs with almost the same RBM frequency, i.e. 1 1/cm compared to ± 1 1/cm for the whole diameter range. The D line often shows a complex shape including up to three components, which makes the identification of correlations with RBM frequencies possible only in selected cases.