15.6: Compton Scattering

Describe the interaction between photons and matter using the Compton effect.

In Compton scattering, a photon interacts with a free electron. The Compton effect is when a photon that emerges from the interaction has a lower energy and longer wavelength than the incoming photon. The magnitude of the change depends on the direction of the photon after the collision.

Compton scattering provides evidence that light is a collection of discrete quantized energy packets called photons.

• Compton scattering can be explained by treating a photon as a particle and applying conservation of energy and conservation of momentum to the collision between the photon and electron.

• The transfer of a photon’s energy to an electron results in the energy, momentum, frequency and wavelength of the photon changing.

The change in wavelength experienced by a photon after colliding with an electron is related to how much the photon’s direction changes.