# Compton scattering

Compton scattering describes the collision of a photon with, for example, an electron due to subsequent changes in the wavelength of the resulting photon.

### History

In 1905, Albert Einstein introduced the idea of ​​the corpuscular wave character of particles to explain the photoelectric effect . Since, according to her, it was possible to consider a photon to be both a wave and a particle, there should be interactions between it and, for example, an electron, which would correspond in nature to elastic collisions, during which total momentum and energy are conserved within the isolated system.

However, according to the ideas of classical physics, after the collision of a photon with an electron, the electron should be oscillated by the frequency of the incident photon and then send out photons again with the same frequency.

In 1922, Arthur Holly Compton decided to test this theory . He created an X-ray scattering experiment on free electrons. It was necessary to use the impact of radiation on materials with very weakly bound electrons. X-rays (λ = 0.07 nm) hit the carbon target. Compton was able to detect duplicate spectral lines : one corresponded to the original wavelength (scattering on tightly bound electrons), the other had a higher wavelength (scattering on free electrons). The correctness of Einstein's theory was thus experimentally confirmed, and Compton won the Nobel Prize in Physics in 1927 .

### Compton shift

The existence of a second wavelength was expressed by the equation for the Compton shift:

$\lambda '-\lambda ={\frac {h}{m_{0}c}}(1-\cos \varphi ).$ λ ... the wavelength of the photon before the collision

λ´ … the wavelength of the photon after the collision

φ … scattering angle

h/m 0 c ... Compton wavelength (for an electron = 2.4262 · 10-12 m)