Optical Polarizability of Zigzag Single-Walled Carbon Nanotubes Fullerene-Capped at One End and Covalently Bonded with Benzene Rings at the Other End

We report on the results of numerical simulations for the linear optical polarizability of single-walled zigzag (9,0) carbon nanotubes with modified ends. The nanotubes of a variable length are fullerene-capped at one end and covalently bonded to a hydrophobic cluster of nine benzene rings at the other end. We investigate electronic and optical properties of such structures within a framework of the Su-Schrieffer-Heeger model. We demonstrated that the localized states in this system exhibit nonlinear characteristics of excited states. The nanotubes have a strongly oscillating dependence of their optical polarizability on the energy of incident light. Spectral features of the optical polarizability drop in intensity and shift towards higher energies with a decrease in the length of a nanotube or upon fullerene-uncapping. The length dependence is similar for the nanotubes without benzene rings, capped either at one or both ends. Potential applications are suggested for hydrophobic pollutant control in liquid-purification systems.