Nanoparticles by SEM – electron microscopy analysis

Electron microscopy is a powerful technique for studying nanoparticles. However, it can be expensive and labor-intensive. In this method, an electron beam focuses on the sample and scans a defined area. The resulting images are constructed from electrons emitted by the sample surface.

By analyzing these images, researchers can determine the number-weighted size distributions of nanoparticles. They achieve this by identifying each particle individually.

To achieve a representative particle size distribution, we must investigate a sufficient number of nanoparticles. One significant advantage of electron microscopy is its ability to visualize both the size and shape of nanoparticles. This additional data is vital for further quantification and interpretation of specific surface area results obtained from BET surface area analysis. By combining size and shape information, researchers gain a comprehensive understanding of the nanoparticles’ characteristics.

The shape of nanoparticles influences the threshold value of the volume specific surface area. This value is calculated from BET surface area analysis using gas adsorption. While BET surface area analysis often serves as a screening method for detecting nanoparticles, electron microscopy acts as a confirmatory technique.

According to the European Commission’s guidelines on nanoparticle identification, electron microscopy provides direct visualization of nanoparticles. This capability allows for definitive confirmation of their presence. In this context, the adage “seeing is believing” holds true, as researchers can observe nanoparticles directly. This confirmation is crucial for accurate classification and compliance with regulatory standards.

Unlike the differential centrifugal method and dynamic light scattering, electron microscopy requires dry samples. This requirement is similar to the conditions needed for volume specific surface area assessment. Additionally, the sample volume for electron microscopy analyses is very limited.

This limitation necessitates a critical representative sampling step before the actual investigation. Proper sampling ensures that the data collected accurately represents the nanoparticle population. By emphasizing careful sampling, we can enhance the reliability of electron microscopy results.

In our laboratory, we have dedicated sampling equipment to ensure representative sampling. Fortunately, because nanoparticles are very small, researchers can encounter a large number of particles even in a tiny sample volume. This capability allows for accurate and meaningful analysis of nanoparticle characteristics, supporting ongoing research and development in nanotechnology.

The shape of nanoparticles plays a crucial role in quantifying and interpreting the specific surface area results obtained from BET surface area analysis. Specifically, the shape determines the threshold value of the volume specific surface area derived from BET analysis using gas adsorption. While BET surface area analysis is considered a screening method, electron microscopy serves as a confirmatory technique.

According to the European Commission’s guidelines on nanoparticle identification, the BET surface area is an indicator value that suggests potential nanoparticle presence. In contrast, electron microscopy provides direct visual confirmation of nanoparticles, reinforcing the adage “seeing is believing.”

Unlike the differential centrifugal method and dynamic light scattering, electron microscopy requires dry samples. This requirement aligns with the conditions for volume specific surface area assessment. Furthermore, the sample volume for electron microscopy analyses is very limited. Therefore, it is essential to conduct a critical representative sampling step before the actual investigation.

In our laboratory, we have dedicated sampling equipment to ensure representative sampling. Fortunately, nanoparticles are very small, allowing researchers to encounter a large number of particles even in a tiny sample volume. This capability enhances the reliability of our electron microscopy results, supporting accurate nanoparticle characterization.