Skip to main content

Theoretical Study of NMR and Raman Spectra of Functionalized and Intercalated Nanotubes

Final Activity Report Summary - SPECCNT (Theoretical Study of NMR and Raman Spectra of Functionalized and Intercalated Nanotubes)

The discovery of carbon nanotubes (CNT) in the 1990s by Iijima caused a flurry of experimental and theoretical investigations of this fascinating new form of carbon. CNTs are micrometer-long hollow carbon cylinders and can be seen as graphene sheets (honeycomb two-dimensional carbon lattices), rolled-up like a cigarette with nanometer-scale radii. The tubes have extraordinary mechanical and electronic properties, which make them good candidates for nanostructured multifunctional materials.

Very often, the characterisation of CNTs is done using spectroscopic tools. However, this characterisation is generally indirect, i.e. the experimental result is compared to several theoretical models in order to find an agreement. In view of this, it is clear that there is an apparent need in the community for a theoretical description of nanotubes, not only to understand available experimental data, but also to guide future experiments. Therefore, this research project was dedicated to the theoretical and numerical characterisation of intercalated, doped and functionalised carbon nanotubes, using both nuclear magnetic resonance (NMR) and Raman spectroscopies.

With this project we took an important step in this direction, by providing benchmark calculations for the magnetic susceptibility and NMR chemical shift of carbon nanotubes, both isolated and in bundles. Both properties exhibited dependence on the diameter D and the chirality of the tube, even though this dependence was stronger for the susceptibility. Moreover, we calculated the chemical shift of a double-wall tube and found a diamagnetic shift of the isotropic lines corresponding to the atoms of the inner tube because of the effect of the outer tube. This shift was in good agreement with recent experiments and could be explained by demagnetising currents circulating the outer tube.