Graphene and Fullerenes
A semi-metal with minor overlap between the valence and the conduction bands is called graphene. The detailed structure of graphene is described as an allotrope of carbon consisting of a single layer of carbon atoms arranged in a hexagonal lattice. The properties of graphene include electronic, optical, saturable absorption, nonlinear kerr effect and quantum dots. An allotrope of carbon in the form of a hollow sphere, ellipsoid, tube, and many other shapes is called fullerene. Spherical fullerenes or Buckminsterfullerene resemble the balls used in association football.