Energy Dispersive X-ray Spectroscopy (EDS), also referred to as EDX, is a technique used in conjunction with Scanning Electron Microscopy (SEM) . First the area of interest is identified through SEM imaging. X-rays generated by the SEM’s focused electron beam are then collected by the EDS detector where the energy of the X-ray is determined. The number of X-rays are counted for each particular energy and displayed on a graph of counts vs. energy. Since each element releases X-rays with unique energy signatures it is possible to identify the parent atoms from the X-ray spectrum. All elements greater than Beryllium (Be) can generally be detected and quantitative analysis is possible. Element distribution mapping is another useful technique using EDS. During element mapping, one or more X-ray energies corresponding to one or more elements are collected as the SEM scans the electron beam over a selected area. The X-ray data is synchronized with the SEM image and an ‘element image’ is created showing the presence of the selected element throughout the selected area. This can be a powerful tool for determining the distribution of a contaminant or the structure of a sample.