The photoeffect is the emission of electrons by matter under the action of electromagnetic radiation. The phenomenon was discovered by Hertz in 1887 and first explained correctly in 1905 by Einstein, who suggested that light propagates and is absorbed in fixed amounts, or quanta, called photons rather than continuously. Thus, the discovery and subsequent investigation of the photoeffect was an essential contribution to the development of the idea that electromagnetic waves are at the same time a flux of photons. The photoeffect was explained as a process of photon absorption in matter, e.g., in a metal by an electron with a consequent increase in the electron’s kinetic energy. If this became sufficiently high, the electron could leave the metal. Naturally, the same process may take place in an isolated atom. In this book by “atomic photoionization” we mean the removal of one or several electrons from an atom, i.e., its ionization due to photon absorption.
KeywordsPhoton Absorption Ionization Threshold Photoionization Cross Section Partial Cross Section Photoabsorption Cross Section
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