It was recalled that very common defects in nanotubes were pentagon-heptagon pairs, in which the replacement of four hexagons by two pentagons and two heptagons disrupted the perfect hexagonal lattice. It was demonstrated here that these defects could be eliminated efficiently with the help of femtosecond laser pulses. By performing non-adiabatic molecular dynamics simulations, it was shown that in the laser-induced electronic non-equilibrium the pentagon-heptagon pair was transformed back into four hexagons without causing any irreversible damage to the rest of the nanotube.

Femtosecond Laser Nanosurgery of Defects in Carbon Nanotubes. A.H.Romero, M.E.Garcia, F.Valencia, H.Terrones, M.Terrones, H.O.Jeschke: Nano Letters, 2005, 5[7], 1361-5