PLASMONS ON SPHERICAL CARBON SHELLS

When applied to nonplanar surfaces, the concept of surface plasmons discovered by Ritchie is useful in interpreting spectroscopic and cohesive properties of nanoscopic objects. In this paper, we compare the surface plasmons on spherical shells of a homogeneous, isotropic material with those of a shell made of an anisotropic material arranged in concentric layers. As an example, spherical carbon shells having a graphitic, onion-like structure are shown to have plasmons which cause an ultraviolet Mie absorption distinct from that of planar graphite. The implication for the possible presence of graphitic onions in interstellar dust is discussed.