RAMAN-SPECTROSCOPY OF PRISTINE AND DOPED SINGLE WALL CARBON NANOTUBES

Pulsed laser vaporization (PLV) of a heated, Fe/Ni or Co/Ni catalyzed carbon target in Argon gas has been used to synthesize single-wall car bon nanotubes (SWNTs). The Raman spectrum of SWNTs is very different f rom that observed for graphite (the nanotube's Bat parent) and these d ifferences can be understood as a result of the cyclic boundary condit ion imposed on a graphene sheet rolled up to form a seamless nanotube. Optical resonances are observed which are associated with the one-dim ensional character of the electronic states of these novel quantum wir es. The high frequency tangential mode frequency is significantly upsh ifted (downshifted) when the SWNT bundles are exposed to acceptor (don or) dopants. (C) 1998 Elsevier Science S.A. All rights reserved.