The intermediate frequency Raman mode (IFM) in the range from 300 to 500 cm −1 of individually suspended single-walled carbon nanotubes (SWCNTs) was assessed to determine the effects of chirality and defect density. Photoluminescence spectroscopy was employed to confirm isolation and chirality of the SWCNTs. The IFM frequency exhibited a positive correlation with the nanotube diameter, as expected from prior studies. Raman and photoluminescence measurements were conducted simultaneously with the introduction of defects into a SWCNT. The photoluminescence intensity showed the largest reduction rate among all optical peaks analyzed. Furthermore, the intensity of the IFM increased with defect creation and showed almost the same behavior as the D-mode intensity. These results can be explained by the increase of the exciton−phonon coupling in the defective SWCNTs. Unambiguous chirality assignment using photoluminescence spectroscopy, along with employment of individually suspended samples that minimize environmental effects, enabled us to investigate the intrinsic nature of the IFM.