Nanosurgery in Carbon Nanotubes: Efficient Elimination of Pentagon-Heptagon Defects Using Femtosecond Laser Pulses

Using non-adiabatic molecular dynamics simulations we demonstrate that femtosecond laser pulses are able to eliminate pentagon-heptagon defects within carbon nanotubes. We conclude that ultrafast healing of zig-zag and armchair nanotubes can be achieved with pulse durations of 50~fs within a wide range of laser intensities. This nonthermal transition occurs at a relatively low lattice temperature ($\sim$450 K) and is driven by the electronic entropy, which is dramatically increased by the action of the laser pulse, thus causing 5-7-5-7 defects to become unstable at very high electronic temperatures. The intermediate steps of the inverse Stone-Wales-type transformation are qualitatively different from those occurring in thermally driven phenomena.