Modification of Nanodiamonds by Xenon Implantation: A Molecular Dynamics
  Study
  Xenon implantation into nanodiamonds is studied using molecular dynamics. The
nanodiamonds range in size from 2-10 nm and the primary knock-on (PKA) energy
extends up to 40 keV. For small nanodiamonds an energy-window effect occurs in
which PKA energies of around 6 keV destroy the nanodiamond, while in larger
nanodiamonds the radiation cascade is increasingly similar to those in bulk
material. Destruction of the small nanodiamonds occurs due to thermal annealing
associated with the small size of the particles and the absence of a heat-loss
path. Simulations are also performed for a range of impact parameters, and for
a series of double-nanodiamond systems in which a heat-loss path is present.
The latter show that the thermal shock caused by the impact occurs on the
timescale of a few picoseconds. These findings are relevant to ion-beam
modification of nanoparticles by noble gases as well as meteoritic studies
where implantation is proposed as the mechanism for xenon incorporation in
pre-solar nanodiamonds.
