Single atom force measurements: mapping potential energy landscapes via electron beam induced single atom dynamics

TL;DR

This paper demonstrates how single atom dynamics under electron beam irradiation can be used to map potential energy landscapes in solids, advancing understanding of beam-induced atomic processes and enabling atom-by-atom fabrication.

Contribution

It introduces a method to use a dopant atom as a force sensor to reconstruct potential energy landscapes from electron beam interactions.

Findings

Reconstructed potential energy landscape of a single atom in graphene.

Mapped atomic-scale potentials along step edges.

Quantified beam-induced atomic forces and dynamics.

Abstract

In the last decade, the atomically focused beam of a scanning transmission electron microscope (STEM) was shown to induce a broad set of transformations of material structure, open pathways for probing atomic-scale reactions and atom-by-atom matter assembly. However, the mechanisms of beam-induced transformations remain largely unknown, due to an extreme mismatch between the energy and time scales of electron passage through solids and atomic and molecular motion. Here, we demonstrate that a single dopant Si atom in the graphene lattice can be used as an atomic scale force sensor, providing information on the random force exerted by the beam on chemically-relevant time scales. Using stochastic reconstruction of molecular dynamic simulations, we recover the potential energy landscape of the atom and use it to determine the beam-induced effects in the thermal (i.e. white noise) approximation. We further demonstrate that the moving atom under beam excitation can be used to map potential energy along step edges, providing information about atomic-scale potentials in solids. These studies open the pathway for quantitative studies of beam-induced atomic dynamics, elementary mechanisms of solid-state transformations, and predictive atom-by-atom fabrication.