IR and Raman spectroscopy has been used to study the evolution of the vibrational spectrumof bundled single-walled carbon nanotubes (SWNTs) during the purification process needed to removemetal catalyst and amorphous carbon present in arc-derived SWNT soot. We have carried out a systematicstudy to define the different outcomes stemming from the purification protocol (e.g., DO, DO/HCl, DO/HNO
3, H
2O
2, H
2O
2/HCl), where dry oxidation (DO) or refluxing in H
2O
2 was used in a first purification stepto remove amorphous carbon. The second step involves acid reflux (HCl or HNO
3) to remove the residualgrowth catalyst (Ni-Y). During strong chemical processing, it appears possible to create additional defectswhere carbon atoms are eliminated, the ring structure is now open, localized C=C bonds are created, andO-containing groups can be added to this defect to stabilize the structure. Evolution of SWNT skeletaldisorder obtained via chemical processing was studied by Raman scattering. Higher intensity ratios of R-and G-band (I
R/I
G) are more typically found in SWNT materials with low D-band intensity and narrow G-bandcomponents. Using IR transmission through thin films of nanotubes, we can resolve the structure due tofunctional groups that were present in the starting material or added through chemical processing. Afterhigh-temperature vacuum annealing of the purified material at 1100
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C, IR spectroscopy shows that mostof the added functional groups can be removed and that the structure that remains is assigned to the one-and two-phonon modes of SWNTs.