scattering

scattering [ME, scateren] , a change in the direction of photons caused by the interaction between photons and matter. In coherent scattering, an incident photon interacts with matter and excites an atom, causing it to vibrate. The vibration causes the photon to scatter. In unmodified scattering, a small amount of energy changes the direction of the photon path with no net absorption of energy from the original source. In Compton scattering an incident photon interacts with an orbital electron, transferring some of its energy to that electron. The electron is ejected, and the photon is scattered. Also called Thompson scattering, unmodified scattering. See also Compton scatter.