Читать книгу Essentials of Nuclear Medicine Physics, Instrumentation, and Radiation Biology - Rachel A. Powsner - Страница 17

The electron volt is a special unit defined as the energy required to move one electron against a potential difference of one volt. Conversely it is also the amount of kinetic (motion) energy an electron acquires if it “falls” through a potential difference of one volt. It is a very small unit on the everyday scale, at only 1.6 × 10^–19 joules (J), but a very convenient unit on the atomic scale. One joule is the Système International (SI) unit of work or energy. For comparison, 1 J equals 0.24 small calories (as opposed to the kcal used to measure food intake).

Figure 1.5 An electron shell is a representation of the energy level associated with an atomic electron.

Figure 1.6 K, L, and M electron shells.