FULLERENES, FULLERANES AND THE DIFFUSE INTERSTELLAR BANDS

A theory is described in which the diffuse interstellar bands and the far-ultraviolet extinction are both carried by the recently discovered quasi-spherical carbon shell molecules known as the fullernes, and by their hydrides, the fulleranes. The central theme is hydrogenation: hydrogen atoms covalently bonded to the surface of a fullerane change the structure of the pi-electron system and thereby modify the optical properties, determining not only the diffuse band spectrum of the molecule but also the ultraviolet cross-section. It is supposed that the physical and chemical environment in the interstellar medium controls the degree of this hydrogenation, so that changes in the environment give rise to spatial changes in the optical and ultraviolet properties of the medium. The theory gives some account of the known tendency of the lambda-4430-angstrom family to be weak both in the diffuse clouds of the interstellar medium and in directions in which the far-ultraviolet extinction is high.