Читать книгу Essentials of Nuclear Medicine Physics, Instrumentation, and Radiation Biology - Rachel A. Powsner - Страница 50

Charged particles (alphas, betas, and positrons) interact with the electrons surrounding the atom’s nucleus by transferring some of their kinetic energy to the electrons. The energy transferred from a low‐energy particle is often only sufficient to bump an electron from an inner to an outer shell of the atom. This process is called excitation. Following excitation, the displaced electron promptly returns to the lower‐energy shell, releasing its recently acquired energy as an X‐ray in a process called de‐excitation (Figure 2.8). Because the acquired energy is equal to the difference in binding energies of the electron shells and the binding energies of the electron shells are determined by the atomic structure of the element, the X‐ray is referred to as a characteristic X‐ray.