Compton's effect

Compton's effect is based in Compton Scattering. Compton Scattering is an inelastic scattering because the wavelength of scattered light differs from the incident radiation for instance photon and an electron. Nuclear Compton scattering exists, but usually Compton scattering refers to the interaction between the electrons of an atom. The changed wavelength is called the Compton shift. Part of the energy of the photon is transferred to the scattering electron, which results in a decrease in photon's energy, this is called the Compton effect. Inverse Compton scattering may also occur when electron transfers part of its energy to a photon.

It was observed in the early 20th century, that when X-rays with known wavelength interact with atoms, the X-rays are scattered through an angle and emerge with a different wavelength. The scattered x-ray photon has less energy, it has a longer wavelength and less penetrating than the incident photon.

Compton's effect is important because demonstrates that light cannot be explained purely as a wave phenomenon. The classical theory of an electromagnetic wave cannot explain low intensity shifts in wavelength for that it must behave as particles to explain low-intensity Compton scattering.

Energy and momentum are conserved in this process so it is not generally possible for the electron simply to move in the direction of the incident photon. The interaction between electrons and high -energy photons results in the electron being given part of the energy. If the scattered photon still has enough energy, the process may be repeated.