Covalent Bond Formation to a Carbon Nanotube Metal

摘要

The pseudo-one-dimensional (psuedo-1D) conjugated electronic structure of single-walled carbon nanotubes (SWNTs) allows them to exhibit semiconducting and metallic properties and to exhibit ballistic transport. We show that their unique electronic structure also offers the opportunity for new horizons in chemistry by exploring the response of the Fermi level (E_F) elec-tronic structure of the metallic SWNTs to carbon-carbon bond formation at the nanotube surface. Ionic chemistry (doping) with electron acceptors introduces holes into the valence band of the nanotubes that can lead to the removal of the in-terband transition between the first set of singularities in the density of states (DOS) of the semiconducting SWNTs. However, the most prominent modification to the spectra of the hole-doped SWNTs occurs in the far-infrared (FIR), where there is a very strong increase in the intensity of excitations near E_F due to intra-band transitions. Although ionic chemistry does not change the band structure, it does create partially filled metallic bands, and the local electrostatic fields, due to the counterions, are too weak to cause localization.