Which interaction primarily involves loosely bound outer-shell electrons?

Which interaction primarily involves loosely bound outer-shell electrons?

• A. Photoelectric interaction
• B. Compton interaction
• C. Coherent scatter
• D. Pair production

Answer: (B)

The interaction described is Compton scattering. In this process a photon collides with a relatively loose or quasi-free electron and transfers part of its energy to that electron, causing the photon to scatter at a lower energy and a recoil electron to be produced. Outer-shell electrons have low binding energies, so they behave almost like free electrons, making Compton scattering the dominant mechanism for photons interacting with these loosely bound electrons at moderate energies. In contrast, the photoelectric effect mainly involves ejecting tightly bound inner-shell electrons, which is why it is more sensitive to binding energy and atomic structure; coherent (Rayleigh) scattering is elastic and involves the whole atom with negligible energy transfer, and pair production requires photon energy above 1.022 MeV and involves creating an electron-positron pair in the nuclear field.

The interaction described is Compton scattering. In this process a photon collides with a relatively loose or quasi-free electron and transfers part of its energy to that electron, causing the photon to scatter at a lower energy and a recoil electron to be produced. Outer-shell electrons have low binding energies, so they behave almost like free electrons, making Compton scattering the dominant mechanism for photons interacting with these loosely bound electrons at moderate energies.

In contrast, the photoelectric effect mainly involves ejecting tightly bound inner-shell electrons, which is why it is more sensitive to binding energy and atomic structure; coherent (Rayleigh) scattering is elastic and involves the whole atom with negligible energy transfer, and pair production requires photon energy above 1.022 MeV and involves creating an electron-positron pair in the nuclear field.