S. Suzuki et al., Electronic structure at carbon nanotube tips studied by photoemission spectroscopy - art. no. 245418, PHYS REV B, 6324(24), 2001, pp. 5418
The valence band and C 1s photoemission spectra were measured from the tips
and the sidewalls of multiwalled carbon nantoubes grown on Si substrates.
The results show an overall spectral shift to the higher-binding-energy sid
e, a larger density of states at the Fermi level, and a lower work function
at the tips. These results can be explained by assuming that the Fermi lev
el is slightly shifted upward and located inside the conduction band at the
tips. We suggest that the electronic structure at the tips is considerably
affected by defects.