Electronic structure of the Fe-layer-catalyzed carbon nanotubes studied by x-ray-absorption spectroscopy.

X-ray-absorption near edge structure (XANES) measurements have been performed to investigate the local electronic structures of the Fe-catalyzed and stabilized carbon nanotubes (CNT) with various diameters. The intensities of the π[sup *]- and σ[sup *]-band and the interlayer-state features in the C K-edge XANES spectra of these CNTs vary with the diameter of the CNT. The white-line features at the C K- and Fe L[sub 3]-edges suggest a strong hybridization between the C 2p and Fe 3d orbitals, which lead to an enhancement of the C K- and reduction of the Fe L[sub 3]-edge features, respectively, indicative of a charge transfer from C 2p to Fe 3d orbitals. The Fe K-edge spectra reveal a p–d rehybridization effect that reduces p-orbital occupation at the Fe site. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]