Curvature-induced bonding changes in carbon nanotubes investigated by electron energy-loss spectrometry

TLDR

The study investigates how curvature‑induced strain alters covalent bonding in single‑ and multi‑shell carbon nanotubes using electron energy‑loss spectroscopy of the core K level. EELS measurements of the core K level were combined with first‑principles local‑density calculations to link spectral features to atomic interactions in the nanotubes. Results show that curvature and layer stacking modify the σ* conduction states while leaving the π* band unchanged even at 7° corrugation, and the covalent character of bonding in existing nanotubes is discussed. © 1996 The American Physical Society.

Abstract

Effect of curvature-induced strain on the covalent bonding in isolated and selected single-shell and multi- shell carbon nanotubes is explored, using electron energy-loss spectroscopy (EELS) on the core K level, which probes the distribution of available unoccupied states in the conduction band. Results show that the curvature and mostly the layer stacking affect the \ensuremath{\sigma}* conduction states. On the contratry, no influence is detected concerning the \ensuremath{\pi}* band, even with corrugation angles up to 7\ifmmode^\circ\else\textdegree\fi{} in a 1-nm-wide single-walled tube. First-principle local-density calculations are used to relate the features in the EELS spectra to the different atomic interactions in nanotubes. Finally, the covalent character of the bonding in existing nanotubes is discussed. \textcopyright{} 1996 The American Physical Society.