Scanning electron microscopy with energy-dispersive X-ray spectroscopy

Scanning electron microscopy (SEM) combined with energy dispersive X-ray spectroscopy (EDS or EDX) generates a sharp picture of the microscopic surface structures of the sample as well as provides accurate information about its elemental composition.

This combination of two techniques is suitable for almost all kinds of samples and has a huge number of applications from basic scientific research to product development and quality control.

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Scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX, also called SEM-EDS) is a combination of two effective techniques, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX or EDS). With SEM, the microscopic surface structures of the sample can be seen with high precision and more closely than with a traditional light microscope. A scanning electron microscope can have a resolution less than 1 nm, which is much higher than a light microscope has.  Therefore a more high-quality and accurate image of the sample’s surface topography is obtained with SEM. More information about the SEM operating principle can be found from our SEM page.

The EDX detector

A large selection of needs both in science and industry can be met with SEM, because a lot of different accessories can be added to the microscope to get different kinds of information about the sample. When the elemental composition of the sample is wanted to determine, an additional EDX detector is attached to the SEM machine. An EDX detector identifies the elements in the sample along with determining their concentrations and distribution.

The operation principle of EDX

The EDX detector detects the X-rays which are produced by the material when electrons interact with its surface during SEM imaging. EDX analyses the X-rays and can therefore identify all other elements in the sample except hydrogen, helium and lithium. The elements in the sample can be distinguished from each other because every element has its own kind of X-ray spectrum which they emit after interacting with the electrons. When the elemental compositions of different parts of the sample is known, it can be concluded what compounds the sample contains. Finally, this information about different spectra from different parts of the sample can be visualized for example in an elemental map of the sample’s surface where different elements and compounds have been marked with different colors.

More information about the interaction happening in the sample can be found from our XRF page. In X-ray fluorescence (XRF), the same phenomenon is utilized to identify elements as in SEM-EDX but with the help of X-rays instead of electrons.

Suitable sample matrices

  • Solid samples
  • Different materials such as metals or polymers
  • Powders

Ideal uses of SEM-EDX

  • Identification of different elements along with determination of their concentrations and distribution in small areas of the sample’s surface for instance to clarify the causes of chemical reactions with the help of elemental mapping
  • Product development, quality control and process optimization for example with the help of defect analysis, process characterization, analysis of breaking mechanisms and particle identification
  • Searching extra substances by identifying elements in the sample for example to find food contaminants or other compounds that do not belong in the material of interest
  • Study of complex environmental and biological samples to find out the structures and compositions of their surfaces

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Frequently asked questions

What is SEM-EDX commonly used for?

SEM-EDX has many applications for example in industrial manufacturing and materials science. It is also useful for energy and resource management as well as for examination of consumer-packaged articles. With SEM-EDX large, heavy and challenging samples can be examined with an excellent image quality showing the tiniest details and chemical composition of the surface of the material. 

SEM-EDX is commonly used in product development: failure and defect analyses, process characterization as well as particle kind and size determination and material classification can be performed with the help of SEM-EDX to ensure the quality of the product along with optimizing its production processes. Reverse engineering and breaking mechanism analyses are also possible to do with SEM-EDX. Deeper structural analysis of different materials, for example examination of surface topology, detection of surface contamination as well as determination of the causes of chemical reactions, such as corrosion and oxidation with the help of SEM-EDX can be very useful for the research and development work. 

Elemental mapping, where different elements and compounds detected by the EDX detector are marked with different colors in the picture, is an effective method for seeing the elemental composition of a sample at a glance. It can also be found out if the produced material has some additional substances, and at which point of the manufacturing process they have ended up in it by using SEM-EDX. 

The elemental composition of a sample can also be determined with X-ray fluorescence (XRF) among other methods. In XRF, a similar phenomenon is utilized as in SEM-EDX.

What are the limitations of SEM-EDX?

With SEM only the surface structures of the sample can be examined if the sample and its inner parts are wanted to keep in one piece and undamaged.

If the sample is too large for the microscope, it may also need some cutting before the analysis. Other sample preparation techniques are usually needed if the sample is dirty, wet or does not conduct electricity. 

The analysis and possible coating of the sample in SEM-EDX may also limit possible subsequent analyses. Some elemental peaks can overlap in the X-ray spectrum of the sample which means that thorough analysis of the results is needed to distinguish the elements from each other accurately. It also has to be acknowledged that hydrogen, helium and lithium can not be discovered with EDX. The size of the area analysed with SEM-EDX ranges approximately from 0.1 to 3 micrometers. 

What kind of samples can be analyzed with SEM-EDX?

Solid samples can be analysed with SEM-EDX. If the sample is dry and conducts electricity, SEM or SEM-EDX does not require pretreatment of the sample and does not damage the material. If the sample does not meet these requirements, it must often be prepared before SEM: cleaning, fixing, drying, attaching to a platform and coating with metal or carbon has to be done before imaging.

What is Measurlabs?

Measurlabs offers a variety of laboratory analyses for product developers and quality managers. We perform some of the analyses in our own lab, but mostly we outsource them to carefully selected partner laboratories. This way we can send each sample to the lab that is best suited for the purpose, and offer high-quality analyses with more than a thousand different methods to our clients.

How does the service work?

When you contact us through our contact form or by email, one of our specialists will take ownership of your case and answer your query. You get an offer with all the necessary details about the analysis, and can send your samples to the indicated address. We will then take care of sending your samples to the correct laboratories and write a clear report on the results for you.

How do I send my samples?

Samples are usually delivered to our laboratory via courier. Contact us for further details before sending samples.

SEM-EDX (or SEM-EDS) enables quick and accurate imaging of microscopic surface structures and determination of elemental composition for all kinds of materials from metals to biological tissues. Measur guarantees reliable results for your samples and strong quality control for your products with effective SEM-EDX analysis. This measurement is an inexpensive all-around tool for achieving your product development goals.