Comparative study on raman and photoluminescence spectra of carbon nanotubes dispersed in different surfactant solutions

Raman and photoluminescence (PL) spectra of HiPCO and CoMoCat single-walled carbon nanotubes (SWCNTs) dispersed in 1 wt% aqueous surfactant solutions with five different surfactants were studied. The SWCNT suspensions exhibit almost the same Raman spectra, regardless of the surfactant used, but the PL peak positions of all the observed (7,5), (6,5), (8,3), (9,1), and (6,4) SWCNTs show strong surfactant-dependent shifts as large as ∼19 meV, known as solvatochromic shifts. For SWCNTs dispersed in deoxycholate sodium salts and sodium dodecyl sulfate solutions, the amount of the solvatochromic shift decreases as the excitation laser power is increased.