Electronic structure and radial breathing mode for carbon nanotubes with ultra-high curvature

peer reviewedUltra-high curvature single-walled carbon nanotubes (SWCNTs) with diameters down to 0.37 nm were prepared by transformation of FeCp(2) peapods to double-walled CNTs (DWCNTs). Results from resonance Raman scattering and high resolution transmission electron microscopy (TEM) were compared to calculations on the molecular dynamical, many electron corrected extended tight binding, and density functional theory (DFT) level. The growth process was found to be catalytic from Fe(3)C particles inside the tubes with dimensions of a crystallographic unit cell. The electronic structure showed dramatic deviations from tight binding results. The family behavior leads to level crossing already for E(11) and E(22) transitions. Experimental results fitted well into a Kataura-Popov plot and allowed assignment for the observed Raman lines of the inner tubes. Experimental and calculated radial breathing mode (RBM) frequencies showed a systematic difference indicating a radial expansion of the smallest inner tubes and a radial compression for the larger tubes. (c) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei