Which radiation type results from outer-shell electrons filling vacancies in inner shells, emitting photons with characteristic energies?

Which radiation type results from outer-shell electrons filling vacancies in inner shells, emitting photons with characteristic energies?

• A. Characteristic
• B. Photoelectric
• C. Compton
• D. Brems

Answer: (A)

When an inner-shell vacancy is created, an electron from a higher shell drops down to fill it. This transition releases energy as a photon with an energy equal to the difference between the binding energies of the two shells. Because these energies are specific to the element, the emitted photons have discrete, characteristic energies—hence the term characteristic radiation. This is different from other interactions: the photoelectric effect involves ejecting an electron and not emitting a photon with a fixed energy; Compton scattering is the inelastic scattering of a photon off an electron, changing the photon's energy and direction; Bremsstrahlung is braking radiation produced by decelerating electrons, which yields a continuous spectrum rather than sharp lines.

When an inner-shell vacancy is created, an electron from a higher shell drops down to fill it. This transition releases energy as a photon with an energy equal to the difference between the binding energies of the two shells. Because these energies are specific to the element, the emitted photons have discrete, characteristic energies—hence the term characteristic radiation.

This is different from other interactions: the photoelectric effect involves ejecting an electron and not emitting a photon with a fixed energy; Compton scattering is the inelastic scattering of a photon off an electron, changing the photon's energy and direction; Bremsstrahlung is braking radiation produced by decelerating electrons, which yields a continuous spectrum rather than sharp lines.