In Compton interactions, what shell do x-ray photons primarily interact with in atoms?

In Compton interactions, x-ray photons primarily interact with the outermost shell of electrons in atoms. This is because the energy of x-ray photons typically corresponds to the binding energies of the electrons in these outer shells. As the incident photon interacts with an outer shell electron, it transfers some of its energy to the electron, causing it to be ejected from the atom, while the photon itself is scattered at a different angle with reduced energy.

The outermost shell, or valence shell, contains electrons that are less tightly bound to the nucleus compared to those in inner shells. This makes them more susceptible to interaction with incoming photons. Therefore, during a Compton interaction, the photon primarily collides with these outer electrons, leading to the characteristic scattering effects observed in this type of interaction.