Raman and IR Spectroscopy of Chemically Processed Single-Walled Carbon Nanotubes

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• 作者：Un Jeong Kim ; Clascidia A. Furtado ; Xiaoming Liu ; Gugang Chen ; and Peter C. Eklund
• 刊名：Journal of the American Chemical Society
• 出版年：2005
• 出版时间：November 9, 2005
• 年：2005
• 卷：127
• 期：44
• 页码：15437 - 15445
• 全文大小：210K
• 年卷期：v.127,no.44(November 9, 2005)
• ISSN：1520-5126

文摘

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/HNO₃, H₂O₂, H₂O₂/HCl), where dry oxidation (DO) or refluxing in H₂O₂ was used in a first purification stepto remove amorphous carbon. The second step involves acid reflux (HCl or HNO₃) 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 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.