Fig. 1

a Raman spectra of SWCNTs excited at 785 nm in the presence and absence of 25 mM solutes, expressed relative to the intensity at 236 cm⁻¹ for the no additive sample; note that the spectra for no additive and urea overlap each other. b Solute concentration dependence of the Raman spectra at 236 cm⁻¹. c Ratios of the spectral intensity at 268 cm⁻¹ to that at 236 cm⁻¹ as a function of the salt concentration