Particle Size Determination Using TEM: A Discussion of Image Acquisition and Analysis for the Novice Microscopist

TLDR

Nanoparticle synthesis advances demand reliable size‑distribution analysis, and TEM provides near‑atomic imaging, yet the choice of imaging mode, magnification, and analysis method trades off resolution, contrast, particle count, and beam damage. This study examines how these critical TEM imaging decisions influence the statistical properties of nanoparticle size distributions.

Abstract

As nanoparticle synthesis capabilities advance, there is an increasing need for reliable nanoparticle size distribution analysis. Transmission electron microscopy (TEM) can be used to directly image nanoparticles at scales approaching a single atom. However, the advantage gained by being able to "see" these nanoparticles comes with several tradeoffs that must be addressed and balanced. For effective nanoparticle characterization, the proper selection of imaging type (bright vs dark field), magnification, and analysis method (manual vs automated) is critical. These decisions control the measurement resolution, the contrast between the particle and background, the number of particles in each image, the subsequent analysis efficiency, and the proper determination of the particle-background boundary and affect the significance of electron beam damage to the sample. In this work, the relationship between the critical decisions required for TEM analysis of small nanoparticles and the statistical effects of these factors on the resulting size distribution is presented.