Let's clarify the nature of these two phenomena:
Photoelectric effect: This refers to the ejection of electrons from the surface of a material when it is exposed to light or other electromagnetic radiation. The key factor determining the occurrence of the photoelectric effect is the energy of the incident photons. For electrons to be emitted, the energy of the photons must be equal to or greater than the binding energy of the electrons within the material. These binding energies can vary for different electron energy levels, including both inner and outer shells. Therefore, electrons from various energy levels can participate in the photoelectric effect.
Compton effect (or Compton scattering): This effect involves the scattering of photons by free electrons or loosely bound electrons in atoms. When a high-energy photon interacts with an electron, it transfers some of its energy and changes its direction. This effect is wavelength-dependent and is observed as a change in the wavelength of the scattered photon. The Compton effect is not limited to outer shell electrons; it can occur with electrons from any energy level.
Both the photoelectric effect and the Compton effect are important phenomena in understanding the behavior of electromagnetic radiation interacting with matter, and electrons from different energy levels can participate in both processes.