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Scanning electron microscopy
Electron Microscopy Service Scanning electron microscopy  ...

The scanning electron microscope (SEM) can offer a varied range of information from the sample surface. It operates by scanning an electron beam over the area of interest (magnifications) while a monitor displays the information selected based on the detectors available. The UPV Microscopy Service has the following detectors:

Secondary electron detector (SE): offers a typical black and white image of the topography of the surface examined. This is the most suitable signal for observing samples as it has the highest resolution.

Backscattered electron detector (BSE): also offers a surface image but with a lower resolution. Its advantage is that it is sensitive to variations in the atomic number of elements on the surface. On a smooth surface you will observe different shades of grey depending on whether there are various phases with different elements.

X-ray detector (EDS): receives X-rays from each point on the surface scanned by the electron beam. As the energy of each X-ray is characteristic for each element, it offers qualitative and quantitative analytical information on areas of the size desired on the surface. For this reason, this technique is known as EDS Microanalysis.

X-ray detector (WDS): similar to the previous detector but instead of receiving and processing the energy of all the X-rays at the same time, it only measures the signal generated by a single element. Although this technique is slower, this makes it much more sensitive and accurate than the EDS. They are complementary, as EDS offers good information on all the elements on the sample surface, and WDS can resolve peaks of elements whose emission energies are very close and it can detect much smaller concentrations of any element, particularly light elements.

Electron backscattered diffraction detector (BSED): in this case it only receives electrons diffracted by the sample surface that comply with Bragg’s law at the point where they are generated, i.e., the signal provides information on the crystalline structure of the sample. If you already know the crystalline phase or phases on your sample, the system can process the signal received as Kikuchi lines and offer varied crystallographic information: grain orientation, relative orientations, texture, phase identification, pressure evaluation, grain borders, grain size, etc.

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