Polarized Raman Study of Aligned Multiwalled Carbon Nanotubes

Polarized Raman spectra of high purity aligned arrays of multiwalled carbon nanotubes, prepared on silica substrates from the thermal decomposition of a ferrocene-xylene mixture, show a strong dependence of the graphitelike $G$ band and the disorder-induced $D$ band on the polarization geometry employed in the experiments. The experimental $G$-band intensity exhibits a minimum at ${\theta }_m=55\mathrm{}°$ in the $\mathrm{VV}$ configuration, in good agreement with theoretical predictions of a characteristic minimum at 54.7° for $A_{1g}$ modes in single wall nanotubes, where ${\theta }_m$ denotes the angle between the polarization direction and the nanotube axis.