Raman spectroscopy on electrochemically doped carbon nanotubes

We studied the Raman response of electrochemically doped single-walled carbon nanotubes (SWNT), using different electrolyte solutions and excitation energies in the range 1.92 - 2.54 eV. The frequency shifts of the high-energy stretching graphite-like mode (HEM) and the IF disorder (D) mode were examined as a function of the doping level. We show that the actuation properties of nanotubes (strain vs. doping) can be determined from the HEM shift. The results, considered in the framework of a double-resonant model for Raman scattering, give evidence about the doping-induced shift of whole regions of phonon dispersion branches.