Single Wall Carbon Nanotubes (SWNTs) are insoluble in most organic solvents, such as toluene. Improvements in the solubility of the SWNTs are, however, seen as a result of interaction with dye molecules such as terphenyl and anthracene. The suspensions formed are stable for periods greater than 24 months. Spectroscopic analysis clearly shows interaction between the SWNTs and dye molecules. The fluorescence of the dye molecules is quenched on interaction with SWNTs, and, in the case of terphenyl, the spectrum is red shifted. Raman spectroscopy of the composites shows vibrations that are not present in either the SWNTs or dye powders. At the position at which these unique Raman peaks occur in the composite spectra, it was found that both the dye and SWNTs had infrared (IR) active vibrations at these wavenumbers. It is therefore thought that the new Raman peaks in the composite samples are possible IR modes that become Raman active on interaction between the dyes and SWNTs. The Radial Breathing Modes (RBMs) give detail as to how diameter selective the dye samples are when compared to the pristine SWNT modes. Red shifting of the RBMs for both composite spectra was observed. It is believed that such a result is due to the debundling of the tubes on interaction with the dye molecules.

Solubilization of single walled carbon nanotubes (SWNT) in the presence of polycyclic aromatic hydrocarbons (PAHs) such as p-terphenyl and anthracene has been shown. The suspensions formed are stable for periods greater than 48 months but to date experimental research is scarce regarding the interactions that are taking place. Spectroscopic analysis such as Raman and fluorescence are used to probe the interactions occurring between the PAHs and the SWNT over a wide concentration range. Previous studies show the fluorescence of the PAHs is quenched on interaction with SWNT and in the case of p-terphenyl, the spectrum is red shifted. This result prompted a study of a large range of concentrations to quantify the degree of interaction between the SWNT and PAHs. It was found at high concentrations that both the PAHs and SWNT formed aggregates and at lower concentrations it was found that free PAHs and isolated SWNT were interacting. The radial breathing modes (RBMs) in Raman spectroscopy gave detail as to how diameter selective the PAH samples are when compared to the pristine SWNT modes. An increase in the wavenumber of the RBMs for both composite spectra was observed and it is believed that such a result is due to the debundling of the SWNT on interaction with the PAHs. It was also found that anthracene and p-terphenyl selectively interact with SWNT and the selected SWNT were found to be within a distinct diameter range and possessed unique physical properties.

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This work is licensed under a Creative Commons AttributionNoncommercial-Share Alike 3.0 License Recommended Citation Gregan, E. et al. (2005) Use of Raman spectroscopy in the investigation of debundling of single walled carbon nanotubes. Proceedings of OptoIreland, 2005. SPIE, vol. 5826, pp.56 ABSTRACTSamples of raw nanotubes are compared to those deposited from solutions to examine separation of nanotube bundles. Single wall nanotubes bundles produced by the arc-discharge and HiPco methods were solubilised in toluene, DMF and 1,2 dichloroethane. Resonant Raman spectroscopy was used to determine if debundling of the tubes sample occurred. The results showed some degree of debundling, best for the 1,2 dichloroethane solvent, which also shows long term solubility.

Abstract. Hybrid systems of the conjugated organic polymer poly (p-phenylene vinylene-co-2,5-dioctyloxy -m-phenylene vinylene) (PmPV) and HiPco SWNT are explored using spectroscopic and thermal techniques to determine specific interactions. Vibrational spectroscopy indicates a weak interaction and this is further elucidated using Differential-Scanning Calorimetry and Temperature Dependent Raman Spectroscopy. Two distinct transitions in region of -60°C and + 60°C are investigated.