Sub-nanometer free electrons with topological charge

TL;DR

This paper presents a theory for focused free electron vortices created via holographic masks, demonstrating excellent agreement with experiments and enabling precise measurement of electron optical parameters.

Contribution

It introduces a comprehensive theory for electron vortices with quantized angular momentum, validated by experimental data, and facilitates measurement of key optical parameters.

Findings

Excellent agreement between theory and experiment

Determination of spherical aberration and coherence parameters

Potential for sub-nanometer electron vortex applications

Abstract

The holographic mask technique is used to create freely moving electrons with quantized angular momentum. With electron optical elements they can be focused to vortices with diameters below the nanometer range. The understanding of these vortex beams is important for many applications. Here we present a theory of focused free electron vortices. The agreement with experimental data is excellent. As an immediate application, fundamental experimental parameters like spherical aberration and partial coherence are determined.