Edge-Detected 4DSTEM -- effective low-dose diffraction data acquisition method for nanopowder samples in a SEM instrument

TL;DR

This paper introduces an effective low-dose diffraction data acquisition method for nanopowder samples in SEMs, leveraging direct electron detectors to enable fast, low-damage analysis of nanoparticles with minimal data storage needs.

Contribution

The work presents a novel diffraction setup and data processing methods for nanoparticle analysis in SEMs, reducing acquisition time and beam damage while enabling efficient data handling.

Findings

Reduced acquisition time for diffraction data

Lowered beam damage and contamination

Significant data reduction and fast processing

Abstract

The appearance of direct electron detectors marked a new era for electron diffraction. Their high sensitivity and low noise opens the possibility to extend electron diffraction from transmission electron microscopes (TEM) to lower energies such as those found in commercial scanning electron microscopes (SEM).The lower acceleration voltage does however put constraints on the maximum sample thickness and it is a-priori unclear how useful such a diffraction setup could be. On the other hand, nanoparticles are increasingly appearing in consumer products and could form an attractive class of naturally thin samples to investigate with this setup.In this work we present such a diffraction setup and discuss methods to effectively collect and process diffraction data from dispersed crystalline nanoparticles in a commercial SEM instrument. We discuss ways to drastically reduce acquisition time while at the same time lowering beam damage and contamination issues as well as providing significant data reduction leading to fast processing and modest data storage needs. These approaches are also amenable to TEM and could be especially useful in the case of beam-sensitive objects.