Stretching of carbon-carbon bonds in a 0.7 nm diameter carbon nanotube studied by electron diffraction

We studied a carbon-carbon bond-length of single-wall carbon nanotube with the diameter in the class of ∼0.7 nm by the electron diffraction. The nanotube, used in this study, was grown as an inner tube of a double wall carbon nanotube (DWNT) from peapod. Taking advantage of the use of DWNT, we can accurately determine the direction of incident electron beam, chiral indices, and both intensities and positions of diffraction spots. Due to careful analyses of these electron diffraction data, it was found that the carbon-carbon bond-length for ∼0.7 nm diameter class of an inner tube is stretched by 0.9±0.1% as compared with that for ∼1.4 nm outer tube. This is experimental evidence indicating a stretching of carbon-carbon bond in the small diameter tube