Energy Dispersive Xray Spectroscopy (EDS)
Energy Dispersive Xray Spectroscopy (EDS), also referred to as EDX analysis, is a technique used in conjunction with Scanning Electron Microscopy (SEM). To begin, the area of interest is identified through SEM imaging. Xrays generated by the SEM’s focused electron beam are then collected by the EDS detector where the energy of the xray is determined. The number of xray images are counted for each particular energy and displayed on a graph of counts vs. energy. Since each element releases xrays with unique energy signatures, it is possible to identify the parent atoms from the xray spectrum. All elements greater than Beryllium (Be) can generally be detected and quantitative analysis is possible.
Element distribution mapping is another useful technique utilizing EDS analysis. During element mapping, one or more xray energies corresponding to one or more elements are collected as the SEM scans the electron beam over a selected area. The xray 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.