Electron spectroscopy studies of carbon nanotubes

Electron spectroscopies play an essential role in the experimental characte rization of the electronic structure of solids. After a short description o f the techniques used, the paper reviews some of the most important results obtained on purified single- and multi-wall carbon nanotubes, and intercal ated nanotubes as well. An analysis of the occupied and unoccupied electron states, and the plasmon structure of the nanotubes is provided. How this i nformation can be used to characterize the samples is discussed. Whenever p ossible, a comparison between nanotube data and those from graphite and C-6 0 fullerene is made, as to draw a coherent picture in the light of recent t heories on the electronic properties of these C-sp(2) materials.