Rutherford backscattering theory

RBS is based on collisions between atomic nuclei and derives its name from Lord Ernest Rutherford, who in 1911 was the first to present the concept of nuclei in atoms. It involves measuring the number and energy of ions in a beam, which backscatter after colliding with atoms in the near-surface region of a sample where the beam has been targeted. With this information, determining atomic mass and elemental concentrations versus depth below the surface is possible. RBS is ideally suited for determining the concentration of trace elements heavier than major 

The numbers of backscattering events that occur from a given element in a sample depend upon two factors the concentration of the element and the 

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