Hooray!!! This issue of the PNAS contains an article co-authored by Rodrigo Capaz: “Systematic determination of absolute absorption cross-section of individual carbon nanotubes”.

In this contribution, they develop a technique to determine the cross section for light absorption of a single carbon nanotube at a time! Comparing with theory, they were able to understand how the absorption spectra relate to the exciton oscillator strength and lifetime, as well as the chirality of the nanotube under analysis.
http://www.pnas.org/content/111/21/7564.abstract