▎ 摘　　要

We discuss recent measurements of the interband spectrocopy of carbon nanotubes and studies of cyclotron resonance in graphene, using these to examine the possible dependence of the band structure of graphene on the number of layers present and the role of Coulomb interactions. Cyclotron resonances gives a value for the electron velocity at the Dirac point of 1.093 x 10(6) ms(-1), which is similar to 20% larger than would be expected from deductions of the band structure of carbon nanotubes. In addition, a significant asymmetry exists between band structure for electrons and holes, which gives rise to a 5% difference between the velocities at energies of 125 meV away from the Dirac point.