Metrological Investigation of the (6,5) Carbon Nanotube Absorption Cross Section

Using single-nanotube absorption microscopy, we measured the absorption cross section of (6,5) carbon nanotubes at their second-order optical transition. We obtained a value of 3.2 × 10<sup>–17</sup> cm<sup>2</sup>/C atom with a precision of 15% and an accuracy below 20%. This constitutes the first metrological investigation of the absorption cross section of chirality-identified nanotubes. Correlative absorption–luminescence microscopies performed on long nanotubes reveal a direct manifestation of exciton diffusion in the nanotube.