Initial Publication Date: May 17, 2007

Generation of Characteristic X-Rays

Darrell Henry, Louisiana State University

Energy shells associated with electron excitation

Characteristic X-rays are generated when an energetic beam of electrons interacts with the inner shell electrons by inelastic scattering with enough energy to excite inner shell electrons to outer shell orbitals, leaving inner-shell vacancies. As outer-shell electrons fall to the various inner shell orbitals, characteristic amounts of energy are generated that are a function of the target element and the type of orbital decay. Much of the energy is emitted from the atom or some may be internally absorbed and knock out another outer shell electron (Auger electron) with additional energy emissions.

These phenomena are useful because:
  • There is a relationship between energy (E) and the wavelength (λ) given by the expression: λ = 12.398/E (where λ is in Å