Statistical analysis of the electronic structure of single-wall carbon nanotubes

The electronic structure of single-wall nanotubes in intact, undissolved ``buckypaper'' has been studied using scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) at 23 K. STM topography shows, that single-wall carbon nanotubes (SWNT's) form microbundles that in turn aggregate in ropes. STS allows us to distinguish between room temperature metallic and wide-gap SWNT's. We find a distribution ratio of (49±7)%:(51±7)%, respectively. A statistical analysis of the observed band gaps and metallic plateaus within these groups is carried out and used to determine the diameter distribution of the SWNT's in the buckypaper.