Highly Extended Image States around Nanotubes

We predict that freely suspended, linear molecular conductors or dielectrics, such as carbon nanotubes, can support electronic states that are localized far from the surface. These “tubular image states” are formed in extended potential wells resulting from the tug of war between the external electron’s attraction to its image charge in the nanotube, and its repulsion from the tube due to its transverse angular momentum. The displacement of these states (>10   nm) away from the surface prevents their wave functions from collapsing, resulting in long lifetimes at low temperatures. We predict that tubular image states with binding energies of 1–10   meV can be formed via radiative recombination.