Cost & Capability Compromises in STEM Instrumentation for Low-Voltage Imaging

TL;DR

This paper uses image simulations to analyze how different instrument parameters affect low-voltage STEM imaging of nanoparticles, providing a methodology for optimizing energy spread for better resolution.

Contribution

It introduces a simulation-based methodology to determine the optimal energy spread for low-voltage STEM, aiding cost-effective instrument optimization.

Findings

Optimal energy spread can be deduced for specific STEM setups.

Chromatic aberration correction improves low-voltage imaging resolution.

Methodology aids in making informed, economical instrument choices.

Abstract

Low voltage transmission electron microscopy (<=80 kV) has many applications in imaging beam-sensitive samples, such as metallic nanoparticles, which may become damaged at higher voltages. To improve resolution, spherical aberration can be corrected for in a Scanning Transmission Electron Microscope (STEM), however chromatic aberration may then dominate, limiting the ultimate resolution of the microscope. Using image simulations, we examine how a chromatic aberration corrector, different objective lenses, and different beam energy-spreads each affect the image quality of a gold nanoparticle imaged at low voltages in a spherical aberration-corrected STEM. Quantitative analysis of the simulated examples can inform the choice of instrumentation for low-voltage imaging. We here demonstrate a methodology whereby the optimum energy spread to operate a specific STEM can be deduced. This methodology can then be adapted to the specific sample and instrument of the reader, enabling them to make an informed economical choice as to what would be most beneficial for their STEM in the cost-conscious landscape of scientific infrastructure.