Enhanced optical absorption cross-section characteristics of multi-wall carbon nanotubes

The optical absorption anisotropy of multi-walled carbon nanotubes (MWCNTs) has been quantitatively characterized through the determination of the absorbance and the degree of linear polarization. A model considering the orientation of the MWCNTs and the sensitivity to both co-polarized and cross-polarized radiation, through electric field depolarization effects, was used to understand the experimental results. The MWCNT optical absorption cross-sections for both the co-polarized radiation (∼0.1 Å2/atom) and the cross-polarized radiation (∼0.05 Å2/atom) were found to be much larger than for single-walled carbon nanotubes. Our results indicate the promise of MWCNTs for applications involving radiation absorption.