Raman spectra have been demonstrated repeatedly to be a very valuable tool for the analysis of new carbon phases such as fullerenes and single wall carbon nanotubes (SWCNTs). Recently it was ...demonstrated from TEM analysis that C60 can be encapsulated into SWCNTs. The structures have been given the name ‘peapods’. The concentration of the encapsulated ‘peas’ and the bonding structure in the tube are still unknown but under heavy discussion. From experience with C60 and SWCNTs, Raman spectroscopy is expected to be a key technique for the analysis of such structures. In our experiments, we found two modes in the region of the pentagonal pinch mode of C60. The resonance behavior for these two modes and their temperature dependence is shown in this paper.
Structural properties of carbon peapods, C-60, trapped into single-walled carbon nanotubes (SWNT), have been studied under high-pressure/high-temperature conditions (HPHT) by in situ x-ray ...diffraction. The C-60 chain structure together with the influence of the filling on the SWNT change under HPHT treatment is investigated. Synthesis of a one-dimensional polymer chain of C-60 inside the single-walled carbon nanotubes is evidenced. At 4 GPa, increasing the temperature up to 1023 degrees C leads to a progressive C-60 polymerization that is associated to a shortening of C-60-C-60 distance down to 8.7 A. Back to ambient conditions, the C-60 chain remains polymerized, emphasizing the high stability of this material. In addition, our data strongly suggest a symmetry change of the two-dimensional bunde lattice under pressure.
We have measured local electronic transport through a junction of single-wall carbon nanotube (SWNT) bundles by atomic force microscopy/scanning tunneling spectroscopy dual-probe method. We found ...that (1) there was a sudden decrease in the current near the junction of SWNT bundles and (2) the current actually flowed through the junction of SWNT bundles. From the observed topographic current image, we can expect our method to be a powerful technique for the investigation of functions of the devices in the nanometer scale.
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