EDS Energy dispersive X-ray spectroscopy (EDS) measures the energy distribution of X-rays emitted from a sample irradiated with an electron beam. Incident electrons cause the electrons of some atoms to be raised temporarily to  higher energy levels. As these electrons return to their original energy levels, they release energy in the form of X-rays. Different atoms have different available energy levels for their electrons. Consequently, different elements have different characteristic X-ray energy distributions (spectra). Analysis of the spectra from a point or region in a sample provides information about the elements present and their proportions. The distributions of an element in a region of the sample can be mapped by recording counts within a particular energy range of the spectra at each point on a grid.   EDS spectrum (left) and EDS map (right)