# How to image single isolated atoms by using coherent low-energy electrons

## TL;DR

This paper shows how low-energy electrons can be used to image single atoms by analyzing interference patterns in electron holography.

## Contribution

The study identifies specific conditions for imaging single atoms using low-energy electron holography.

## Key findings

- Single atoms produce interference patterns with concentric fringes detectable by low-energy electrons.
- The diffraction angle depends on source-to-sample distance and is consistent across different electron energies and atom types.
- Results align with recent experiments on alkali atoms in graphene structures.

## Abstract

Coherent low-energy electrons have been demonstrated as a practical tool for imaging individual macromolecules and two-dimensional (2D) crystals. Low-energy electrons exhibit unique properties: low radiation damage to biological molecules and high sensitivity to the local potentials. In this study, we outline the conditions at which single isolated charge-free atoms can be imaged by low-energy electron holography. A single atom produces an interference pattern consisting of concentric fringes of finite diameter and of very weak intensity. The diffraction angle θ, determined as the first minimum of the concentric rings interference pattern, exhibits similar dependency on the source-to-sample distance zs as sinθ ∼ 0.3/zs1/2 for electrons of different energies (50, 100 and 200 eV) and scattered off different elements (Li, C, and Cs). The results are compared to the recently reported experimental holograms of alkali atoms intercalated into bilayer graphene and adsorbed on top of graphene.