Controlling atomic joints between carbon nanotubes by electric current.

Using a transmission electron microscope and a nanomanipulator, we explored the early head-to-head coalescence of two capped carbon nanotubes (CNTs) under induction of electric current. We measured detaching forces for coalesced CNTs, showing discrete identifiable values attributable to van der Waals interaction, single sp2-like bonds, and double sp3-like bonds by comparing them with forces obtained using molecular dynamics simulations. Our results underscore the feasibility of atomically controlled junctions of CNTs tuned by the amount of the electrical current.