Interaction of Elemental Particles with Matter

Materials are made up of chemical compounds that in turn are formed by atoms. Atoms have essentially a dense nucleus around which a cloud of electrons balances the electrical charge of the nucleus. If high-energy electrons are shot at matter, some will bounce off the surface, some will penetrate into it producing X-rays, while others will interact with the higher energy electrons (inner shell electrons) of the atoms. These are the principles used for SEM, EDS and wavelength dispersive X-ray spectroscopy (WDS). 

Scanning Electron Microscopy. A useful tool for investigation of the surface appearance of materials and any changes after treatment is the SEM. This tool is widely available in universities and some art museums. The principle of 

EDS is a fast technique that can produce qualitative elemental information within a few minutes. Although the computer will process results in a 

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