Intensity Ratio of Resonant Raman Modes for ($n,m)$ Enriched Semiconducting Carbon Nanotubes

Relative intensities of resonant Raman spectral features, specifically the radial breathing mode (RBM) and G modes, of eleven, chirality-enriched, single-wall carbon nanotube (SWCNT) species were established under second-order optical transition excitation. The results demonstrate a significantly under-recognized complexity in the evaluation of Raman spectra for the assignment of ($n,m)$ population distributions. Strong chiral angle and mod dependencies affect the intensity ratio of the RBM to G modes and can result in misleading interpretations. Furthermore, we report five additional values for chirality dependent G$^{+}$ and G$^{-}$ Raman peak positions and intensities, supporting accuracy in literature values, and extending the available data to cover more of the small diameter regime by including the first (5,4) second-order, resonance Raman spectra. Together, the Raman spectral library is demonstrated to be sufficient for decoupling multiple species via a spectral fitting process, and enable fundamental characterization even in mixed chiral population samples.