We present a resonance Raman study of electrochemical charge transfer doping on polyelectrolyte single-walled carbon nanotubes (SWNTs) in solution. Changes in the intensity of the radial breathing modes of well-identified SWNTs are measured as a function of the electrochemical potential. The intensity is maximum when the nanotubes are neutral. Unexpectedly, the Raman signal decreases as soon as charges are transferred to the nanotubes, leading to intensity profiles that are triangular for metallic and trapezoidal for semiconducting nanotubes. A key result is that the width in energy of the plateaus for the semiconducting nanotubes is roughly equal to the optical gap (rather than the free carrier gap). While these experiments can be used to estimate the energy levels of individual nanotubes, strong dynamical screening appears to dominate In individual SWNT polyelectrolytes so that only screened energy levels are being probed.
Raman Doping Profiles of Polyelectrolyte SWNTs in Solution / Dragin F.; Penicaud A.; Iurlo M.; Marcaccio M.; Paolucci F.; Anglaret E.; Martel R.. - In: ACS NANO. - ISSN 1936-0851. - STAMPA. - 5:(2011), pp. 9892-9897. [10.1021/nn203591j]
Raman Doping Profiles of Polyelectrolyte SWNTs in Solution.
IURLO, MATTEO;MARCACCIO, MASSIMO;PAOLUCCI, FRANCESCO;
2011
Abstract
We present a resonance Raman study of electrochemical charge transfer doping on polyelectrolyte single-walled carbon nanotubes (SWNTs) in solution. Changes in the intensity of the radial breathing modes of well-identified SWNTs are measured as a function of the electrochemical potential. The intensity is maximum when the nanotubes are neutral. Unexpectedly, the Raman signal decreases as soon as charges are transferred to the nanotubes, leading to intensity profiles that are triangular for metallic and trapezoidal for semiconducting nanotubes. A key result is that the width in energy of the plateaus for the semiconducting nanotubes is roughly equal to the optical gap (rather than the free carrier gap). While these experiments can be used to estimate the energy levels of individual nanotubes, strong dynamical screening appears to dominate In individual SWNT polyelectrolytes so that only screened energy levels are being probed.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
