NationMaster - Encyclopedia: Auger effect

The Auger effect (pronounced /ˡɔːʒɚ/, or Oh' jeh) is a phenomenon in physics in which the emission of an electron from an atom causes the emission of a second electron.^[1] When an electron is removed from a core level of an atom, leaving a vacancy, an electron from a higher energy level may fall into the vacancy, resulting in a release of energy. Although sometimes this energy is released in the form of an emitted photon, the energy can also be transferred to another electron, which is ejected from the atom. This second ejected electron is called an Auger electron.^[2] Articles with similar titles include the NATO phonetic alphabet, which has also informally been called the â€œInternational Phonetic Alphabetâ€. For information on how to read IPA transcriptions of English words, see IPA chart for English. ... This is a discussion of a present category of science. ... For other uses, see Electron (disambiguation). ... For other uses, see Atom (disambiguation). ... Secondary emission is a phenomenon that occurs in electron tubes where electrons impact an electrode with sufficient energy to knock additional electrons from the surface of that electrode. ... For other uses, see Electron (disambiguation). ... For other uses, see Atom (disambiguation). ... In modern physics the photon is the elementary particle responsible for electromagnetic phenomena. ...

Upon ejection the kinetic energy of the Auger electron corresponds to the difference between the energy of the initial electronic transition and the ionization energy for the electron shell from which the Auger electron was ejected. These energy levels depend on the type of atom and the chemical environment in which the atom was located. Auger electron spectroscopy involves the emission of Auger electrons by bombarding a sample with either X-rays or energetic electrons and measures the intensity of Auger electrons as a function of the Auger electron energy. The resulting spectra can be used to determine the identity of the emitting atoms and some information about their environment. Auger recombination is a similar Auger effect which occurs in semiconductors. An electron and electron hole (electron-hole pair) can recombine giving up their energy to an electron in the conduction band, increasing its energy. The reverse effect is known as impact ionization. The kinetic energy of an object is the extra energy which it possesses due to its motion. ... Molecular electronic transitions take place when valence electrons in a molecule are excited from one energy level to a higher energy level. ... The ionization energy (IE) of an atom or of a molecule is the energy required to strip it of an electron. ... Example of a sodium electron shell model An electron shell, also known as a main energy level, is a group of atomic orbitals with the same value of the principal quantum number n. ... Auger electron spectroscopy is an analytical technique in surface chemistry and materials science. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... A semiconductor is a solid whose electrical conductivity is in between that of a conductor and that of an insulator, and can be controlled over a wide range, either permanently or dynamically. ... For the following two reasons the electron hole was introduced into calculations: If an electron is excited into higher state it leaves a hole in its old state. ... Impact ionization is the process in a material by which one energetic charge carrier can lose energy by the creation of other charge carriers. ...

The name "Auger effect" comes from one of its discoverers, Pierre Victor Auger, and not from the similarly-named device, the auger. Pierre Victor Auger (May 14, 1899 - December 25, 1993) was a French physicist, born in Paris. ... Study of a man using an auger, for The Seven Sorrows of the Virgin, Albrecht DÃ¼rer, ca 1496 An auger is a device for moving material or liquid by means of a rotating helical flighting. ...

History

The Auger emission process was discovered in the 1920s by Lise Meitner, an Austrian physicist. The Auger effect was discovered in 1925 by Pierre Victor Auger upon analysis of a Wilson cloud chamber experiment. High energy X-rays were applied to ionize gas particles and observe photoelectric electrons. Observation of electron tracks independent of the frequency of the incident photon energy suggested a mechanism for electron ionization that was caused from an internal conversion of energy of from a radiationless transition. Further investigation and theoretical work showed that the effect was a radiationless effect more than an internal conversion effect by use of elementary quantum mechanics and transition rate and transition probability calculations. (ref 1) Lise Meitner ca. ... Pierre Victor Auger (May 14, 1899 - December 25, 1993) was a French physicist, born in Paris. ... The photoelectric effect is the emission of electrons from matter upon the absorption of electromagnetic radiation, such as visible light or ultraviolet radiation. ... . Internal conversion is a radioactive decay process where an excited nucleus interacts with an electron in one of the lower electron shells, causing the electron to be emitted from the atom. ...

History

See also

References