Energy Dispersive X-Ray Spectroscopy (EDS): While in a Scanning Electron Microscope (SEM), samples are exposed to high energy electrons in a vacuum, which generates X-rays through secondary electron transitions.  Variations in electron configuration specific to each element generate different energy electrons, and thus different signature energy peaks, indicating which elements are present in the sample.  Analysis is performed only on areas which are exposed to the electron beam, facilitating precise control of the analyzed area.  This means the composition of very small areas or particles in a sample can be taken.  Since EDS is performed in the SEM chamber, a quick and easy interrogation of the surface materials as viewed on the SEM is possible.  This can be expanded to include the entire sample, please see our Elemental Mapping page.  Additionally, relative amount of the elements present can be calculated, generating composition percentages.