Which interaction ejects a photoelectron due to inner-shell vacancy?

Which interaction ejects a photoelectron due to inner-shell vacancy?

• A. Compton scattering
• B. Pair production
• C. Photoelectric absorption
• D. Coherent scattering

Answer: (C)

When a photon with enough energy interacts with an atom, it can be absorbed by ejecting an electron from one of the inner shells. This process creates an inner-shell vacancy and is called photoelectric absorption. The ejected electron, a photoelectron, carries kinetic energy equal to the photon’s energy minus the binding energy of the ejected inner-shell electron. The vacancy that results is often filled by electrons from higher shells, which can emit characteristic X-rays or Auger electrons as part of the relaxation. Other interactions don’t produce a photoelectron due to an inner-shell vacancy: Compton scattering involves transferring some energy to a loosely bound or free electron, ejecting it, but not because of a specific inner-shell vacancy; the energy transfer is in a scattering process. Pair production creates an electron-positron pair in the nuclear field at sufficiently high energy, not related to inner-shell vacancies. Coherent (Rayleigh) scattering is elastic and leaves the atom ionized, with no electron ejection.

When a photon with enough energy interacts with an atom, it can be absorbed by ejecting an electron from one of the inner shells. This process creates an inner-shell vacancy and is called photoelectric absorption. The ejected electron, a photoelectron, carries kinetic energy equal to the photon’s energy minus the binding energy of the ejected inner-shell electron. The vacancy that results is often filled by electrons from higher shells, which can emit characteristic X-rays or Auger electrons as part of the relaxation.

Other interactions don’t produce a photoelectron due to an inner-shell vacancy: Compton scattering involves transferring some energy to a loosely bound or free electron, ejecting it, but not because of a specific inner-shell vacancy; the energy transfer is in a scattering process. Pair production creates an electron-positron pair in the nuclear field at sufficiently high energy, not related to inner-shell vacancies. Coherent (Rayleigh) scattering is elastic and leaves the atom ionized, with no electron ejection.