The interaction of nitrogen molecules with (4, 0) single-walled carbon nanotube: electronic and structural effects.

The electronic structure and energetics of (4, 0) single-walled carbon nanotubes (CNTs) interacting with nitrogen have been studied using density-functional calculations. We show that the nanotubes become covered with a stable sheath of N(2) molecules. We have constructed potential energy curves which can be used for the thermodynamic analysis of N(2) adsorption and desorption processes. Our results show that any analysis of the observed properties (for example thermodynamics, stability, and photoluminescence) of air-exposed CNTs needs to consider the N(2) adsorbed on the CNTs.