Quantitative Analysis of Isolated Single‐Wall Carbon Nanotubes with Their Molar Absorbance Coefficients

The molar absorbance coefficients of metallic, semiconducting, and (6,5) chirality enriched single‐wall carbon nanotubes were evaluated by a spray technique combined with atomic force microscopy. Single‐wall carbon nanotubes with isolated and a single predominant electronic type were obtained by using the density‐gradient ultracentrifugation technique. In the visible region, all coefficients had similar values around 2–5 × 109/mL mol−1 cm−1, independent of their diameter distribution and the electronic types of single‐wall carbon nanotubes, and the εS22/εM11  and εS11/εM11 were estimated to be 1.0 and 4.0, respectively. The coefficient strongly depends on the length of single‐wall carbon nanotubes, independent of their electronic types and chirality.