The most common BSE detectors are solid state detectors which typically contain p-n junctions. SE imaging can provide more detailed surface information. BSE images show high sensitivity to differences in atomic number: the higher the atomic number, the brighter the material appears in the image. Therefore, BSE and SE carry different types of information. They give information about the elemental composition of the sample.īSE come from deeper regions of the sample, while SE originate from surface regions. X-rays These characteristic X-rays are produced when electrons hit the sample surface. Secondary electrons, originate from the atoms of the sample: they are a result of inelastic interactions between the electron beam and the sample. They are very sensitive to surface structure and provide topographic information. These come from within a few nanometers of the sample surface, with a lower energy compared to the backscattered electrons. Backscattered electrons are reflected back after elastic interactions between the beam and the sample. They provide compositional information and lower resolution images. They originate from deep within the sample (a few microns below the surface) and interact strongly with the sample. Backscattered electrons (BSE) These are high energy electrons, scattered out of the sample and only losing a small amount of energy.When high energy electrons reach the sample, several electron and X-ray signals are generated. All these different types of signals carry different useful information about the sample and it is the choice of the microscope’s operator which signal to capture. In Fig.1, you can see the various products that are possible as a result of the interaction between electrons and matter. As the name implies, electron microscopes employ an electron beam for imaging.
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