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Probing Charge Transfer between Shells of Double‐Walled Carbon Nanotubes Sorted by Outer‐Wall Electronic Type
Author(s) -
Kalbac Martin,
Green Alexander A.,
Hersam Mark C.,
Kavan Ladislav
Publication year - 2011
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201100590
Subject(s) - carbon nanotube , raman spectroscopy , materials science , tube (container) , atomic physics , molecular physics , excitation , nanotechnology , chemistry , optics , composite material , physics , quantum mechanics
Double‐walled carbon nanotubes (DWCNTs) with outer metallic (M) or semiconducting (S) shells were sorted by density‐gradient ultracentrifugation and examined by Raman spectroscopy and in situ Raman spectroelectrochemistry. The combination of sorting and the selection of appropriate laser excitation energies allowed the disentanglement of the effects of different variations of the electronic type (M or S) of the inner and outer tubes in DWCNTs on the doping behavior and charge transfer between the inner and outer walls. Charge transfer from the outer tube to the inner tube occurs only if the electronic states of the outer tube are filled with electrons or holes, and if these filled states are higher in energy than those of the inner tube. Therefore, each combination of inner and outer tube (i.e., inner@outer: M@M, M@S, S@M, and S@S) exhibits a distinct behavior. The potential needed to observe the effects of charge transfer between the inner and outer tubes is found to increase in the following order: M@M < S@M < M@S < S@S.