Exciton dynamics for single walled carbon nanotubes in the presence of a single ion

We study the dynamics of excitons in single walled carbon nanotubes in the presence of a single ion placed on the surface of the tube. The scattering process is described in three main stages. First, we solve the Schr\"{o}dinger equation in the tight binding approximation to calculate the quasiparticle wave functions and energies. Second, we use quasiparticle wave functions and energies in the Bethe-Salpeter equation to calculate exciton binding energies and wave functions. Finally, we use the exciton energies and wave functions to investigate the process of exciton-ion scattering. We model the potential of the single ion by that of a point charge. Our studies show exciton trapping in the presence of the ion.