Characteristics of the Raman spectra of single-walled carbon nanotube bundles under electrochemical potential control.
Resonant Raman scattering spectra of single-walled carbon nanotube-sodium dodecyl sulfate (SWNT-SDS) bundles adsorbed on Au electrodes have been investigated in aqueous electrolytes. Raman intensities of the radial breathing mode (RBM) with 785-nm laser excitation were monitored at different electrode potentials between -0.5 and +0.8 V relative to the SCE. Six resolved RBM peaks assignable to different diameter tubes all decreased in intensity when the electrode was positively biased, because of depletion of valence-band electrons associated with resonant excitation. The attenuation occurred at more positive potentials for narrower-diameter tubes with higher RBM frequencies consistent with their larger bandgaps. The results suggest the Fermi level is equilibrated in bundled SWNTs in contrast with the large Fermi-level shifts reported for isolated SWNTs.
Takeda
Norihiko
N
Japan Science and Technology Agency (JST), Sapporo, 060-0810, Japan.
Murakoshi
Kei
K