Optical properties of the semiconductor carbon nanotube intramolecular junctions

The pi-orbital tight-binding model and sum-over-state method have been used to study the linear polarizability absorption spectra of several intramolecular junctions (IMJs) connecting two semiconductor single-wall carbon nanotubes (SWNTs), whose atomic structures are optimized with a combination of density-functional theory (DFT) and the universal force field (UFF) method. Our results indicate that IMJs optical properties are influenced by different topological defects and their distributions on the interfaces, making the absorption spectra exhibit some new characters, e.g., some new absorption peaks appear together with the original characteristic peaks of two SWNTs on either side. It is suggested that the optical absorption could be used for a supplemental experimental tool to distinguish the topological defect structures of IMJs. (C) 2004 Elsevier B.V. All rights reserved.