Electronic and optical properties of alkali-metal-intercalated single-wall carbon nanotubes

We present recent studies of the structural and electronic properties of alkali-metal intercalated single-wall carbon nanotubes using high-resolution electron energy-loss spectroscopy (EELS) in transmission. Changes in the nanotube structure and electronic properties due to intercalation were monitored by in situ EELS measurement. The modulation of the nanotube bundle structure is reflected by the variations of the diffraction patterns. The core-level excitations show that there is no hybridization between nanotube ${\pi }^{\star }$ states and metal valence states. The intensity of the interband transitions is dramatically affected, demonstrating the possibility of tuning the Fermi level to specific bands upon intercalation. The charge carrier plasmon depends on both the intercalation level and the alkali metal. The loss function was analyzed using a Drude-Lorentz model to obtain more information about the optical properties.