# Modification of Nanodiamonds by Xenon Implantation: A Molecular Dynamics Study

## TL;DR

This study uses molecular dynamics to explore how xenon implantation affects nanodiamonds of various sizes, revealing size-dependent destruction mechanisms and thermal effects relevant to nanoparticle modification and meteoritic xenon incorporation.

## Contribution

It provides new insights into the size-dependent response of nanodiamonds to xenon implantation and the thermal dynamics involved, which were not previously characterized.

## Key findings

- Small nanodiamonds are destroyed at ~6 keV PKA energy due to thermal annealing.
- Larger nanodiamonds exhibit damage patterns similar to bulk diamond.
- Thermal shock occurs within a few picoseconds during impact.

## Abstract

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.