Importance of Compton Scatter

The significance of Compton's effect is that it shows that light cannot be explained solely as a wave phenomenon. As demonstrated in experiments, the classical theory of an electromagnetic wave cannot explain low-intensity wavelength shifts because that radiation must behave as particles to explain low-intensity Compton scattering.

As shown in the figure above, because energy and momentum are conserved in this process, the electron cannot simply move in the direction of the incident photon. When electrons interact with high-energy photons, a portion of the energy is transferred to the electrons, allowing them to change their direction. The process can be repeated if the scattered photon still has enough energy, but as previously stated, the penetrating energy of this same photon is much lower, and the process can be repeated until the photon loses its penetrating energy.