Chemical bonding assisted damage production in single-walled carbon nanotubes induced by low-energy ions

Using first-principles molecular dynamics (MD) and classical MD simulations, we investigate the minimum energy required for various incident ions to displace a carbon atom in single-walled carbon nanotubes (CNTs), which is a key parameter to characterize the damage capability of the incident ion. The role of chemical aspects of incident ions played in the damage production mechanism was analyzed in details. The results indicate that the chemical bonding properties of impinging ions could greatly lower the threshold displacement energy of carbon atoms in CNTs, and thus considerably enhance their damage capabilities compared to those chemically inactive ions. The strong chemical interactions existing between ions and nanotubes can considerably increase the amount of damages, which is in contrast with the conventional conclusion that the damage yield increases monotonically with the atomic number of incident ion owing to its dependence on the cross section of defect production. This chemical bonding assisted damage process is clearly different from the damage process resulted only from physical collisions.