Formation of ion-irradiation-induced atomic-scale defects on walls of carbon nanotubes - art. no. 245405

Recent experiments on irradiated carbon nanotubes provide evidence that ion bombardment gives rise to nanotube amorphization and dramatic dimensional changes. Using an empirical potential along with molecular dynamics, we stu dy structure and formation probabilities of atomic-scale defects produced b y low-dose irradiation of nanotubes with Ar ions. For this, we simulate imp act events over a wide energy range of incident ions. We show that the maxi mum damage production occurs for a bombarding ion energy of about 600 eV, a nd that the most common defects produced at all energies are vacancies, whi ch at low temperatures are metastable but long-lived defects. Employing the tight-binding Green's function technique, we also calculate scanning tunne ling microscopy (STM) images of irradiated nanotubes. We demonstrate that i rradiation-induced defects may be detected by STM and that isolated vacanci es may look like bright spots in atomically resolved STM images of irradiat ed nanotubes.