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.