Multi-wall C nanotubes dispersed on graphite on highly oriented pyrolytic graphite substrates were irradiated with Ar+ ions of 30keV. The irradiated samples were investigated by using scanning tunneling microscopy and spectroscopy in air. The irradiation-induced defects appeared as hillock-like protrusions on the nanotube walls; similar to the hillocks observed earlier on ion-irradiated highly oriented pyrolytic graphite. The results were in agreement with recent predictions, which attributed the scanning tunneling microscopy features produced by ion irradiation to local modifications of the electronic structure. Here, √3 x √3 R"-type superstructures were also observed near to some of the defects. After annealing at 450C in a N atmosphere, the irradiated multi-wall C nanotubes were investigated again by scanning tunneling microscopy. The effect of heat treatment upon irradiation-induced nanotube defects was also considered.

Atomically Resolved STM Images of Carbon Nanotube Defects Produced by Ar+ Irradiation. Z.Osváth, G.Vértesy, L.Tapasztó, F.Wéber, Z.E.Horváth, J.Gyulai, L.P.Biró: Physical Review B, 2005, 72[4], 045429 (6pp)