Trapping of metal atoms in vacancies of carbon nanotubes and graphene.

Lattice defects in carbon nanotubes and graphene are created by focusing an electron beam in a scanning transmission electron microscope onto a 0.1 nm spot on the objects. Metal atoms migrating on the graphenic surfaces are observed to be trapped by these defects. Depending on the size of the defect, single metal atoms or clusters of several atoms can be localized in or on nanotubes or graphene layers. Subsequent escape of the metal atoms from the trapping centers gives information about the bonding between the metal atom and the defect. The process of trapping and detrapping is studied in a temperature range of 20-670 degrees C. The technique allows one to place metal atoms with almost atomic precision in graphenic structures and to create a predefined pattern of foreign atoms in graphene or carbon nanotubes.