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Energy-dispersive Spectroscopy (EDS)

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Energy-dispersive spectroscopy (EDS) is one of the primary techniques used to identify chemical constituents in solid materials. Energy-dispersive spectrometers utilize a semiconductor X-ray detection medium (usually silicon). X-ray photons generated from electron beam-induced electron transitions are delivered into a detector containing a semiconductor detection medium (usually silicon) in which the valence band is fully occupied. Energy from incoming X-ray photons is absorbed causing electrons to jump from the valence to the conduction band and results in a small electric pulse with an energy characteristic of the element from which the X-ray photon was derived. Typically, EDS is used qualitatively to determine the chemical consitutuents within a material. When the electron beam is interacting with a sample and the EDS detector is in operation, all of the energies resulting from distinct elements and/or electron shell transitions are simultaneously collected and presented in an energy histogram (Energy vesus counts per second). EDS detectors have considerably lower spectral resolution than WDS spectrometers resulting in significant peak overlaps, higher dection limits, and lower accurancy and precision. However, for basic characterization and phase indentification, the technique is very powerful and requires very little set-up.    

X-ray image generated using an energy-dispersive spectrometer.