Exfoliation of single-walled carbon nanotube bundles under electron beam irradiation

The exfoliation of single-walled carbon nanotubes (SWNT) bundles induced by electron beam irradiation was observed by an electron microscope. An in situ observation of local structure transformation of a SWNT bundle undergoing electron beam irradiation was performed. It was suggested that the high electron density confined in the tubes within the bundle played a key role in the exfoliation process. A high trapped electron density, necessary for exfoliation, could be easily obtained when the bundles were protruding out onto holes in the TEM specimen grid, as the electron irradiation continued. It was shown that the SWNT bundles began to exfoliate when the Coulomb repulsion overcame the van der Waals interaction.