π-Electronic excitations in intercalated carbon nanotubes

The π-electronic excitations of the intercalated carbon nanotubes are studied within the linear response approximation. Intercalation would induce free carriers and thus a new intra-π-band plasmon with the lowest frequency ω_p ∼ 1 eV. The intercalated carbon nanotubes could also exhibit the π plasmon with the highest frequency ω_p > 2γ₀ (the resonance integral γ₀ ∼ 3eV). These two plasmons are affected by the lattice constant, and the magnitude and the direction of the transferred momentum. The intercalation-induced plasmon is sensitive to the change in the free carrier density, but the opposite is true for the π plasmon.