In situ Raman and Vis-NIR spectroelectrochemistry at single-walled carbon nanotubes

The population of valence-band electronic states of single-walled carbon na notubes (SWCNT) was tuned electrochemically in aqueous electrolyte solution . Depending on the applied potential, reversible changes of intensity and f requency of the Raman-active tangential mode and radial breathing mode were observed. The maximum intensity occurs at ca, -0.2 V vs. Ag/AgCl independe nt of the electrode material used as a support (Pt, Au, Hg). SWCNT are sens itive to photoanodic breakdown upon prolonged exposure to anodic bias and l aser light. Reversible bleaching of the first band-gap transition in semico nducting tubes (at 0.7 eV) occurs after anodic polarization. (C) 2000 Elsev ier Science Ltd. All rights reserved.