Scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDS or EDX) generates a sharp picture of the microscopic surface structures of a sample and provides accurate information about its elemental composition. SEM-EDX analysis is suitable for almost all kinds of samples and has a vast number of applications from basic scientific research to product development and quality control.
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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 of less than 1 nm, which is much higher than that of a light microscope. Therefore a more accurate image of the sample’s surface topography is obtained with SEM. More information about the SEM operating principle can be found on our SEM page.
The EDX detector
A large selection of needs both in science and industry can be met with SEM, as a lot of different accessories can be added to the microscope to get different kinds of information about the sample. When the goal is to determine the elemental composition of the sample, 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 on 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
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
Frequently asked questions
SEM-EDX has many applications in industrial manufacturing and materials science. It can also be used for energy and resource management, as well as for the 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 the chemical composition of the surface of the material.
In product development, SEM-EDX is commonly used for failure and defect analyses and process characterization. Particle kind and size determination and material classification can also be performed with the help of SEM-EDX to ensure the quality of the product along with optimizing its production processes. It is also possible to perform reverse engineering and breaking mechanism analyses with SEM-EDX. Deeper structural analysis of different materials, including the 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 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. SEM-EDX can also determine if the produced material has some additional substances, and at which point of the manufacturing process they have ended up in it.
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.
Only the surface structures of the sample can be examined with SEM if the sample and its inner parts need to be kept 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 or wet, or if it 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 a 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 analyzed with SEM-EDX ranges approximately from 0.1 to 3 micrometers.
Solid samples can be analyzed 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 performed before imaging.
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.
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.
Samples are usually delivered to our laboratory via courier. Contact us for further details before sending samples.