In which process is some of the photon's energy used to dislodge an orbital electron, with the remainder given off as a secondary photon?

The process in which some of a photon's energy is utilized to dislodge an orbital electron, while the remainder of the energy is emitted as a secondary photon, is known as Compton scatter. In this interaction, a high-energy photon collides with an outer-shell electron, transferring only part of its energy to the electron in the process. The electron is ejected from the atom, and the photon loses some energy, which decreases its wavelength and changes its direction.

This is in contrast to the photoelectric effect, where an entire photon’s energy is absorbed by an electron, resulting in the complete ionization of the atom, without the emission of a secondary photon. Pair production refers to a process where a photon with sufficient energy creates a particle-antiparticle pair, which does not involve a secondary photon being emitted. Therefore, Compton scatter is the correct answer, as it accurately describes the process of photon energy being partially transferred and results in the emission of a secondary photon.