FORMATION OF NITROGEN-DOPED CARBON DURING ARC-DISCHARGE OF CARBON RODS IN THE PRESENCE OF PYRROLE

When the are vaporization of carbon rods in a helium atmosphere is con ducted in the presence of small amounts of pyrrole, not only does one form nitrogen-doped fullerenes, but also the surface of the carbon rod s becomes coated with a layer of a nitrogen-doped carbon. X-ray diffra ction indicates d spacing expansion, and x-ray photoelectron spectrosc opy confirms that nitrogen doping has occurred at a level of 2.3%. N-1 s spectra reveal a nonuniformity in the distribution of nitrogen atoms relative to carbon. These data are consistent with a model in which s ubstitution of nitrogen occurs at the domain boundaries of the graphit ic particles. A consequence of this doping is a twofold increase in th e electrical conductivity of the carbon. The x-ray photoemission resul ts indicate that N incorporation induces a shift of the valence band t oward the Fermi level. (C) 1996 American Institute of Physics.