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 from gama and x-radiation or any other radiation with high energy. Nuclear Compton scattering exists in rare cases when the radiation interacts with the nucleus of the atom, but usually Compton scattering refers to the interaction between the electrons of an atom and the incident radiation, more commonly visible with the valence electrons of the atom once they are further from the nucleus they are less attracted to it so its easier for this electrons to be scattered. After the electron and radiation interact, the radiation is reflected with a different wave length, this 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, and there fore ,as the energy is proportional to the frequency and wave length, this exchange of energy is the cause of the different wave length. This process 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.However, according to the classic electromagnetism that predicts that radiation behave simply as a wave this different wave length would not exist, this is, if an incident radiation with wave length of, for instance, θ was reflected after electron interaction, it would have θ as wave length, but it doesn't happen. In fact 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 radiation must behave as particles to explain low-intensity Compton scattering. as it was demonstrated in experiences.

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 electrons being given part of the energy which allows them to change their direction. If the scattered photon still has enough energy, the process may be repeated, but as it was said before the penetrating energy of this same photon is much smaller and process may repeat itself until the photon lose its penetrating energy.

Differences between Compton's effect and photo electric effect
Why dont you observe a compton effect with visible light? Quantum Mechanics Questions Answers.com > Wiki Answers > Categories > Science > Physics > Quantum Mechanics

View Slide Show Best Answer Photons propagating at frequencies in the visible light spectrum can knock out electrons from atoms, known as the photoelectric effect, if their energy is greater than the photoelectric work function for that atom. However, at the energies associated with the visible light frequencies, these new photoelectrons will absorb any excess energy of the initial photons and convert it to kinetic energy, meaning that the initial photons vanish. Obviously, if the photons are gone, they can't scatter. Increasing the intensity (brightening) of the photons will cause more electrons to be emitted, but it will not increase their energy since photon energy is a function of its frequency, not quantity.

Photons that retain energy after interacting with an electron via the photoelectric effect are said to undergo Compton scattering. Now, despite what everyone says, if a photon has any amount of energy greater than the applicable photoelectric work function, it can theoretically undergo Compton scattering. Yes, I'm implying that visible light can Compton scatter. However, the probability of Compton scattering at these energies is very low, not to mention these scattered photons would most likely loose all of their energy from all of the other various available atomic interactions before they could even escape the sample, which is a necessary component to measurement (something has to exist in order to be measured). Therefore, the effects of Compton scattering are negligible at visible light energies. In fact, they don't really start becoming noticeable until around energies of 100keV, which is around 105 times greater than the energies associated with visible light. These kinds of energies are associated with x-rays.