Characteristic X-rays are emitted when outer-shell electrons fill a vacancy in the inner shell of an atom, releasing X-rays in a pattern that is "characteristic" to each element. Characteristic X-rays were discovered by Charles Glover Barkla in 1909, [1] who later won the Nobel Prize in Physics for his discovery in 1917.

Characteristic x-rays are emitted from heavy elements when their electrons make transitions between the lower atomic energy levels. The characteristic x-ray emission which is shown as two sharp peaks in the illustration at left occur when vacancies are produced in the n=1 or K-shell of the atom and electrons drop down from above to fill the gap.

Characteristic X-Rays. Characteristic radiation takes place when the incoming electrons collide with the electrons within the heavy metal and knock-out the electrons from the electron shell.

X-rays are generated via interactions of the accelerated electrons with electrons of tungsten nuclei within the tube anode. There are two types of X-ray generated: characteristic radiation and bremsstrahlung radiation.

Explain these properties of x-rays: divergent rays, photon energy, visibility, speed, ability to produce scatter, effect on phosphors, effect on photodetectors, and the ability to cause biological damage. X-rays are a form of invisible electromagnetic radiation and were discovered on November 8, 1895 by Wilhelm Conrad Roentgen.

One type of X-ray, known as the characteristic X-ray, is generated when an electron in the metal atom is kicked out by the high-energy incoming electrons leaving a hole later filled by electrons from a higher energy state.

Since each element has a unique set of energy levels, each element emits a pattern of X-rays characteristic of the element, termed “characteristic X-rays”. The intensity of the X-rays increases with the concentration of the corresponding element.