Transmission ELECTRON MICROSCOPY – TEM

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Measurement description

Typically, several images are taken at different magnifications to get an overview of the sample and answer your question.

Deliverables

• Bright-/dark-field images at multiple magnifications  
• Selected-area electron diffraction (SAED) patterns with indexed rings/spots (where applicable)  
• Optional: TEM-EDX point spectra, line scans or elemental maps

Sample requirements

Typically, powders are deposited on appropriate TEM grids (procedure depends on your question).
Please contact us directly to discuss possibilities for other type of samples.

More information about the method

TEM enables imaging at nanometer resolution by transmitting a high-energy electron beam through an ultra thin specimen. This technique provides direct insight into morphology, crystallinity, and defects within nanomaterials. 

In contrast to Scanning Electron Microscopy (SEM), which primarily probes surface topography, TEM reveals internal structure and lattice information, allowing detailed analysis of grain boundaries, dislocations and inclusions. TEM generally achieves far higher spatial resolution than SEM, making it indispensable to images nanoparticles smaller than 20 nm or features of such sizes on larger samples. 

Analytical modes such as selected-area electron diffraction (SAED) and energy-dispersive X-ray spectroscopy (EDX) can be integrated within TEM, providing crystallographic and compositional data in parallel with high-resolution imaging.

TEM is particularly relevant for:

• Small nanoparticles and nanomaterials (< 25 nm)
• Size/shape distribution of primary nanoparticles vs. agglomerates  
• Crystallinity, twin boundaries, dislocations  
• Hybrid or multi-phase systems  

Measurement description

Typically, several images are taken at different magnifications to get an overview of the sample and answer your question.

Deliverables

• HAADF/bright-field images at multiple magnifications (with their equivalent SEM images)
• Optional: STEM-EDX point spectra, line scans or elemental maps

Sample requirements

Typically, powders are deposited on appropriate STEM grids (procedure depends on your question). 

Please contact us directly to discuss possibilities for other type of samples.

More information about the method

Scanning Transmission Electron Microscopy (STEM) combines aspects of TEM and SEM by scanning a finely focused electron probe across your specimen to produce images in transmission with high resolution. Detectors, like HAADF, provide images in which heavier elements appear brighter, making it ideal to image your compounds with mixed-phase or core–shell architectures. 

Compared to SEM, which collects reflected or emitted electrons from the sample surface, STEM provides information from within the sample. High-angle annular dark-field (HAADF) imaging in STEM yields Z-contrast, enabling visualization of compositional differences at near-atomic resolution. 

The technique is particularly powerful when coupled with spectroscopic methods such as Energy-Dispersive X-ray Spectroscopy (EDX) or electron energy-loss spectroscopy (EELS), making STEM a versatile tool for structural, chemical, and electronic analysis of advanced materials.  

STEM is particularly relevant for

• Core–shell nanoparticles (shell thickness uniformity)
• Hybrids and mixed-phase nanomaterials
• Catalyst supports with metal nanoclusters

Measurement description

Typically, several images are taken at different magnifications to get an overview of the sample.

Deliverables

• High-resolution micrographs (secondary/backscattered)
• Surface feature measurements (cracks, pits, where possible)
• Optional: EDX point spectra, elemental maps, or line scans

Sample requirements

Powders can be drop casted on conductive substrate (procedure depends on your question). 

For films, a conductive mounting is preferred; non-conductive samples can be coated to mitigate charging (procedure depends on your question). 

More information about the method

Scanning Electron Microscopy (SEM) produces high-resolution images by scanning a focused electron beam across the sample surface and detecting secondary and backscattered electrons. SEM excels in revealing surface morphology, texture, and topography with nanometer-scale resolution, far surpassing the capabilities of Optical Microscopy (OM). 

Its depth of field and high resolution make SEM an indispensable tool for studying powders, coatings, films, and microstructured materials. In addition, SEM can be equipped with analytical detectors such as EDX for elemental mapping, extending its utility beyond morphology to compositional analysis.

SEM is particularly relevant for

• Powder morphology and agglomeration (silica, metal, oxide nanoparticles, etc)  
• Coating integrity and roughness; surface cracks and inclusions  
• Foreign particle or contamination ID on devices or films  
• Porous carriers and supports (qualitative pore structure)  

Measurement includes

Typically, the measurement is done on a few images to obtain a good overview of the sample. You can choose between EDX mapping, line scan, or point measurement. 

Deliverables

• Spectra with labeled peaks or elemental tables (atomic/wt%)
• False-color elemental maps and profiles
• Statement of limits (overlaps, light-element sensitivity, etc)  

Sample requirements

See Sample Requirements sections from SEM, STEM, TEM.

More information about the method

EDX is an add-on to SEM, STEM, or TEM, that provides information about the sample composition. It is suitable for almost all sample types and has a vast number of applications from basic scientific research to product development and quality control. 

When the electron beam hits the sample, atoms emit characteristic X-rays. Measuring those reveals which elements are present and how they’re distributed. For bulk or rugged surfaces we typically pair EDX with SEM; for thin specimens we can also run STEM/TEM-EDX. 

Results are semi-quantitative and subject to standards/matrix effects, with lighter elements being more challenging

EDX is particularly relevant for

• Identifying contamination in a sample or inclusions in a surface
• Verifying alloying/dopants in particles or films 
• Mapping core–shell vs. homogeneous particles