Working Principle

As a result of the interaction between high energy electrons and a sample under investigation in an electron microscope, the atoms of this sample are caused to emit X-rays.

An EDS system makes use of the fact that atoms of different chemical elements emit X-rays of different, characteristic energy. The evaluation of the energy spectrum collected by an energy dispersive Si(Li) or SDD X-ray detector allows the determination of the qualitative and quantitative chemical sample composition at the current beam position.

This technique provides a very high spatial resolution since the information is obtained from a very small sample volume in the order of only a few microns. It is therefore also referred to as X-ray microanalysis.

When used with scanning electron microscopes, the EDS system can analyze element distributions along a line (line scan) or within an area of interest (mapping).

Another advantage of the energy dispersive X-ray spectroscopy is that all elements from atomic number 4 (beryllium) up to 95 (americium) contained in the sample can be detected and analyzed simultaneously.