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Energy Dispersive X-ray Spectroscopy (EDS) enables the elemental characterization of specimens in the SEM. Recall from Beam-Sample Interactions that characteristic X-rays are generated via the interaction of the primary electron beam with the specimen.
EDS can be performed on most electron microscopes, including SEM and TEM.
The accelerating voltage must be set to provide sufficient energy to the incident electrons, and the probe current (or spot size) set to optimize the "Dead Time," which is related to signal processing efficiency.
Sufficient energy must be supplied to the specimen to eject electrons from atoms. When higher energy electrons fill the newly formed voids, the energy difference is emitted as a photon. These characteristic energies are known for all elements and can be found on analytical periodic tables.
There is a "sweet spot" for the surface current that optimizes Dead Time, and therefore signal collection and processing.
Care must be taken when analyzing spectra and maps. Artifacts and errors due to how the signal is processed and the specimen itself may distort spectra or maps.
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