Coherent scattering is most likely to occur when an x-ray photon interacts with which of the following?

Coherent scattering is most likely to occur when an x-ray photon interacts with which of the following?

• A. Inner shell electron
• B. Outer shell electron
• C. Atomic nucleus
• D. Whole atom

Answer: (D)

Coherent scattering occurs when the photon interacts with the entire atom as a single scatterer. Because the electron cloud acts as one unit, the interaction is elastic and the photon leaves with essentially the same energy, only the direction changes. This situation is more likely at low X-ray energies, when the wavelength is large compared with atomic dimensions, so the scattered waves from all electrons add in phase. If the photon interacted with a single electron (inner or outer shell), the process would be Compton scattering, which transfers energy to the electron and is inelastic. Interactions with the atomic nucleus are much less probable at typical X-ray energies and follow different scattering dynamics. So, the best fit is interaction with the whole atom.

Coherent scattering occurs when the photon interacts with the entire atom as a single scatterer. Because the electron cloud acts as one unit, the interaction is elastic and the photon leaves with essentially the same energy, only the direction changes. This situation is more likely at low X-ray energies, when the wavelength is large compared with atomic dimensions, so the scattered waves from all electrons add in phase. If the photon interacted with a single electron (inner or outer shell), the process would be Compton scattering, which transfers energy to the electron and is inelastic. Interactions with the atomic nucleus are much less probable at typical X-ray energies and follow different scattering dynamics. So, the best fit is interaction with the whole atom.