A poor man's theory of circular dichroism in single-wall carbon nanotubes
S. V. Goupalov
TL;DR
The paper addresses circular dichroism in semiconducting single-wall carbon nanotubes and critiques the complexity of prior tight-binding treatments. It adopts a multipolar expansion of light–matter interaction combined with zone-folding to derive CD spectra directly, revealing CD as the interference between electric-dipole and magnetic-dipole transitions. The authors provide explicit magnetic-dipole matrix elements and the optical-rotatory strength within the tight-binding framework, and compute CD spectra for representative nanotubes, finding agreement with earlier work that neglected excitons. This work establishes a transparent baseline derivation and a concrete pathway to include excitonic effects in future studies, aiding interpretation of chirality-resolved CD measurements.
Abstract
The theory of circular dichroism in single-wall carbon nanotubes derived within the tight-binding method by a complicated approach in previous work is rederived in a straightforward way using the multipolar expansion of the light-matter interaction.