The electrical conduction variation in stained carbon nanotubes

Carbon nanotubes become stained from coupling with foreign molecules, especially from adsorbing gas molecules. The charge exchange, which is due to the orbital hybridization, occurred in the stained carbon nanotube induces electrical dipoles that consequently vary the electrical conduction of the nanotube. We propose a microscopic model to evaluate the electrical current variation produced by the induced electrical dipoles in a stained zigzag carbon nanotube. It is found that stronger orbital hybridization strengths and larger orbital energy differences between the carbon nanotube and the gas molecules help increasing the induced electrical dipole moment. Compared with the stain-free carbon nanotube, the induced electrical dipoles suppress the current in the nanotube. In the carbon nanotubes with induced dipoles the current increases as a result of increasing orbital energy dispersion via stronger hybridization couplings. In particular, at a fixed hybridization coupling, the current increases with the bond length for the donor-carbon nanotube but reversely for the acceptor-carbon nanotube.

► We develop a microscopic theory for studying the current variation in the stained carbon nanotubes. ► The electric dipoles created from the charge transfer between the coupled orbits of a single wall carbon nanotube and foreign gas molecules suppress the electrical conduction in the carbon nanotube. Owing to the edge states at the ends of the zigzag carbon nanotubes the induced dipole moments at the edges are extremely large. ► The current increases with the stronger orbital hybridization coupling through an increase of orbital level dispersion. ► Furthermore, at a fixed hybridization coupling, the electric current increases with the bond length for the donor-SWNT but decreases for the acceptor-SWNT.