Dependence of Optical Transition Energies on Structure for Single-Walled Carbon Nanotubes in Aqueous Suspension:  An Empirical Kataura Plot

Spectrofluorimetric data for identified single-walled carbon nanotubes in aqueous SDS suspension have been accurately fit to empirical expressions. These are used to obtain the first model-independent prediction of first and second van Hove optical transitions as a function of structure for a wide range of semiconducting nanotubes. To allow for convenient use in support of spectral studies, the results are presented in equation, graphical, and tabular forms. These empirical findings differ significantly from Kataura plots computed using a simple tight-binding model. It is suggested that the empirically based results should be used in preference to conventional model-based predictions in spectroscopic nanotube research.