Electron emission and structural characterization of a rope of single-walled carbon nanotubes

The electron emission and structural properties of an isolated ''rope'' com prised of similar to 70 individual single-walled nanotubes (SWNT's) were in vestigated by measuring the field-emission energy distributions and by usin g field-ion microscopy (FIM). Field-emission energy distributions, obtained under ultrahigh-vacuum conditions, revealed that the emitting nanotube has a large density:of;states near the Fermi energy, with an energy distributi on of emitted electrons close to that predicted by the free-electron theory . Two small features located on the trailing edge of the energy distributio ns are attributed to localized features in the density of states of a SWNT. FIM studies were also performed on the same rope in an attempt to provide structural information about the emitting nanotube. Initial FIM micrographs showed:an uneven distribution of atoms. Eventually, rings of atoms were im aged. The atom placement around an individual ring structure is analyzed an d found to be consistent with that expected from a single (19,13) SWNT.