A Raman spectroscopy study of the solubilisation of SWCNTs by polycyclic aromatic hydrocarbons

The effectiveness of polycyclic aromatic hydrocarbons (PAHs) for selective solubilisation of single walled carbon nanotubes (SWCNTs) has been studied by Raman spectroscopy. Polyphenyl and polyacene PAHs of different lengths are used. Selective interaction between the PAHs and SWCNT is investigated by analyzing the Raman radial breathing modes the frequency positioning of which yields information concerning the diameter distribution of the SWCNT sample. Samples were dispersed at concentrations below the debundling limit and deposited on quartz substrates. A combination of four laser excitation energies was utilized to establish the distribution of diameters present. The results show that the PAHs interact with a range of SWCNT diameters. In general a preference for smaller diameter SWCNTs is evident, although the longer PAHs have the capacity to solubilise larger diameter SWCNTs, due to their increased binding energy. Although a small degree of structural specificity is evident, all PAHs solubilise both chiral and nonchiral SWCNTs.