Raman spectroscopy of iodine-doped double-walled carbon nanotubes

Abstract

We present a Raman spectroscopy study of iodine-intercalated ($p$-type-doped) double-walled carbon nanotubes. Double-walled carbon nanotubes ($\mathrm{DWCNTs}$) are synthesized by catalytic chemical vapor deposition and characterized by Raman spectroscopy. The assignment of the radial breathing modes and the tangential modes of pristine $\mathrm{DWCNTs}$ is done in the framework of the bond polarization theory, using the spectral moment method. The changes in the Raman spectrum upon iodine doping are analyzed. Poly-iodine anions are identified, and the Raman spectra reveal that the charge transfer between iodine and $\mathrm{DWCNTs}$ only involves the outer tubes.