Stability and spectroscopic studies on oxygenated armchair SWCNTs

Abstract

Theoretical studies on the electronic structures and spectroscopy of oxygenated armchair single-walled carbon nanotubes have been carried out using semi-empirical AM1 and INDO/CIS methods as well as density function theory. Based on the B3LYP/3-21G optimized geometries, the energies of the oxygenated SWCNTs have been calculated at B3LYP/6-31G(d) level. The energy gaps of SWCNTs decrease due to the addition of the oxygen atom. The oxygenated SWCNTs, in which the oxygen atoms are located on the vertical bonds relative to the main axis of SWCNTs are more stable than those in which the oxygen atoms are added on the sloping bonds. The first and strongest absorptions in the electronic spectra of the oxygenated SWCNTs computed using INDO/CIS method are red shifted in comparison with those of SWCNTs. The main absorptions in the IR spectra of the oxygenated SWCNTs calculated with AM1 method are blue shifted as compared with those of SWCNTs. These two kinds of oxygenated SWCNTs can be distinguished using the chemical shifts of the bridged carbon atoms calculated at B3LYP/3-21G level.