In situ Raman scattering studies of alkali-doped single wall carbon nanotubes

Electrochemical doping and in situ Raman scattering were used to study char ge transfer in K- and Li-doped single wall carbon nanotubes (SWNT) as a fun ction of alkali concentration. An 8 cm(-1) downshift was observed for the t angential phonon mode of SWNT doped to stoichiometries of KC24 and Li1.25C6 The shift in both systems is reversible upon de-doping despite an irrevers ible loss of crystallinity. These results indicate that the tangential mode shifts result from electron transfer from alkali dopants to the SWNT, and that these modes are only weakly affected by long-range order within the ro pes. (C) 2001 Elsevier Science B.V. All rights reserved.