Origin of Enhanced Zone Lines in Field Desorption Maps

TL;DR

This paper introduces a new simulation method combining electrostatic and interatomic forces to explain the origin of enhanced zone lines in field desorption maps, revealing how force misalignments cause atom impact accumulations.

Contribution

A novel simulation technique that integrates electrostatic forces into molecular dynamics to accurately reproduce zone lines in field desorption maps.

Findings

Electrostatic forces overpower interatomic forces during evaporation in tungsten.

Force misalignment causes atom launch deviations leading to zone line artifacts.

Simulation successfully reproduces the enhanced zone lines observed experimentally.

Abstract

Artifacts in the collective desorption map of the detector hits impede a truthful reconstruction, including enhanced "zone lines" with high atomic impact intensity. Since APT is destructive, simulation is the only approach to explain the origin of these zone lines, but previous work couldn't reproduce them. Here, we use a new simulation technique that adds the full electrostatic forces to the interatomic forces in a molecular-dynamics simulation and eliminates the previous ad-hoc assumptions. We find for the canonical example of tungsten that evaporation happens when the electrostatic force overpowers the interatomic force, and the misalignment of the two forces deviates the launch direction of the atoms in certain zones, giving rise to an accumulation of hit events around zone lines.