Atomic-Scale Insights into Damage Produced by Swift Heavy Ions in Polyethylene

TL;DR

This study combines Monte Carlo and molecular dynamics simulations to analyze the formation and shape of ion tracks in polyethylene, revealing differences between amorphous and crystalline states and the influence of ion velocity.

Contribution

It introduces a combined simulation approach to predict ion track morphology in polyethylene, accounting for material structure and ion velocity effects.

Findings

Circular tracks in amorphous PE

Elliptical tracks in crystalline PE

Track parameters vary with ion velocity

Abstract

We describe the formation of swift heavy ion tracks in polyethylene (PE) by combining the Monte Carlo code TREKIS, which models electronic excitation in nanometric proximity of the ion trajectory, with the molecular dynamics simulating a response of the atomic system to the perturbation. The model predicts circular tracks in amorphous PE but elliptical ones in crystalline PE caused by preferential propagation of excitation along polymer chains during the cooling stage. The obtained track sizes and shapes agree well with the high-resolution microscopy of tracks in PE. The velocity effect in PE is shown: the track parameters differ for ions with the same energy losses but different velocities.