Excitons states and linear absorption spectra of carbon nanotubes with Stone-Wales defects

The exciton states in the single-walled carbon nanotubes (SWNTs) with Stone-Wales (SW) defects are theoretically studied in the tight-binding model. It is found that for the semiconducting zigzag tubes (10, 0) with different concentration of SW defect, the exciton energies move to low energy region with increasing the concentration of SW defect, and the symmetry broken by the SW defects leads to splitting of the degenerate exciton energy levels, which can be seen clearly from the linear absorption spectra of defected SWNTs. As detected from the linear absorption spectra, we can give some information on the concentration of the SW defect existing in the SWNTs.