X-ray microanalysis (EDS) on a SEM or TEM is a valuable tool for research and industry. No other technique can provide so much information so easily about the chemistry of micro-volumes of a material. Many samples require nothing more than positioning of the electron beam onto the area of interest, collecting a spectra, and 30 seconds later you have your answer. Or do you?

Any technique as widespread and straightforward as energy dispersive x-ray spectroscopy is bound to be misused on occasion. It has been my experience that many users either overestimate the capabilities of EDS to answer difficult materials questions or do not fully appreciate the limitations of the technique and how to work around them. These problems tend to show up as the need to analyze increasingly complex samples increases. The following brief description of the physics of electron beam/specimen interaction may be useful in explaining why problems can exist.