Scanning tunneling microscopic investigations were made of nanotube point defects (e.g. vacancies) created by ion irradiation. The defects appeared as hillock-like features in the scanning tunneling microscopic images. These defects were compared with similar features observed in the scanning tunneling microscopic images of as-grown coiled carbon nanotubes. In this case, the observed hillock-like features were attributed to the non-hexagonal carbon rings which were responsible for the growth of bent and coiled nanotube structures. For irradiation, multi-walled carbon nanotubes produced by arc-discharge were dispersed on highly oriented pyrolitic graphite surfaces and irradiated with 30keV Ar+ ions to a dose of 5 x 1011/cm2.

STM Imaging of Carbon Nanotube Point Defects. Z.Osváth, L.Tapasztó, G.Vértesy, A.A.Koós, Z.E.Horváth, J.Gyulai, L.P.Biró: Physica Status Solidi A, 2007, 204[6], 1825-9