Electronic properties of closed cage nanometer-size spherical graphitic particles

We investigate the localization of charged particles by the image potential of spherical shells, such as fullerene buckyballs. These "spherical image states" exist within surface potentials formed by the competition between the attractive image potential and the repulsive centripetal force arising from the angular motion. The image potential has a power law rather than a logarithmic behavior for a nanotube, leading to fundamental differences in the forms for the effective potential for the two geometries. The sphere has localized stable states close to its surface. At low temperatures, this results in long lifetimes for the image states. We predict the possibility of creating image states with binding energies of a few meV around metallic/non-metallic spherical shells by photoionization. Applications and related phenomena are discussed.