129I-MÖssbauer Study of Iodine-Doped Single-Walled Carbon Nanotubes
The 129I-Mössbauer spectroscopy was applied to the iodine-doped single-walled carbon nanotubes (SWNTs) in the region of heavy and medium doping. Two kinds of SWNTs with different synthesis methods were used as samples. For both samples, the iodine in SWNTs in these doping levels was proved to work as electron acceptors in the forms of triiodides (I 3 − ) and pentaiodides (I 5 − ) and to exist as iodine molecules (I2) in addition. Moreover, monoiodide ions (I−) appear additionally. As the doping level decreases, the proportions of triiodide and monoiodide ions increase, whereas those of pentaiodide ions and iodine molecules decrease. This tendency is in common for both kinds of SWNTs. However, the charge distribution of iodides and the ratios of iodine forms are a little different between two kinds of SWNTs, probably because of difference in morphology and remaining catalysts.
KeywordsDoping Level Electric Field Gradient Iodine Atom Iodine Molecule Iodine Species
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