A simple circularity-based approach for nanoparticle size histograms beyond the spherical approximation

Area of Science:

• Materials Science
• Nanotechnology
• Microscopy

Background:

• Conventional Transmission Electron Microscopy (TEM) is standard for nanoparticle characterization.
• Current methods often rely on simplified spherical approximations for size determination.
• Advanced shape descriptors are needed for more accurate analysis of complex nanoparticle assemblies.

Purpose of the Study:

• To develop a generic particle model for reliable size and volume deduction from TEM images.
• To improve the accuracy of particle size histogram determination, especially for coalesced nanoparticles.
• To validate a new analytical approximation using experimental nanoparticle data.

Main Methods:

• A generic particle model based on projected area and perimeter was developed.
• Comparison of the proposed model with spherical and ellipsoidal approximations.
• Analytical approximation using the circularity parameter for size distribution analysis.
• Experimental validation using nanoparticle assemblies from mass-selected cluster deposition.

Main Results:

• The proposed model reliably deduces equivalent particle size (volume information) using projected area and perimeter.
• The circularity parameter-based approximation enhances particle size histogram accuracy.
• Experimental data from TEM images validated the improved procedure.
• The method effectively characterizes nanoparticle assemblies, including multimers.

Conclusions:

• A simple yet effective method for nanoparticle size and volume determination from TEM images is presented.
• The approach offers significant improvements over traditional spherical approximations.
• Accurate perimeter determination in pixelated images is crucial for this method's success.