Strain determination in electrochemically doped single-walled carbon nanotubes via Raman spectroscopy

We studied the Raman response upon electrochemical p-doping of carbon nanotubes. The frequencies of the first- and second-order high-energy modes as excited in the range 477-780 nm were examined as a function of doping level. We relate the doping-induced shifts of selected Raman modes to the dimensional changes of the SWNTs and propose a method to determine their actuation properties from those shifts. The shift of the second-order D mode strongly depends on the excitation energy, which translates to a strong wave-vector dependence of the doping-induced shift of the phonon branches in the vicinity of the K-point of the Brillouin zone.