Optical and Magneto-Optical Properties of Carbon Nanotube Bundles

The optical and magneto-optical properties of carbon nanotube bundles have been studied theoretically. The dielectric and magneto-dielectric functions in the long wavelength limit are calculated from the gradient approximation. A prominent π-plasmon structure at ∼6-7 eV is identified in the electron-energy-loss spectrum. The π plasmon also reveals itself in the reflectance spectrum as a weak but sharp plasmon edge at ∼6-7 eV. The detailed optical spectra depend on the polarization direction of the incident light, the nanotube structure (such as radius, chiral angle, and number of shells), and the magnetic flux through nanotubes. In general, carbon nanotube bundles would maintain the π-plasmon frequency at ∼6-7 eV. This is mainly a consequence of the unique π-band structure of the graphitelike system. The magnetoreflectance spectra would exhibit a strongly periodical oscillation during the variation of magnetic flux.