![]() The three general classes of radioactive nuclei are characterized by a different decay process or set of processes: We begin this section by considering the different classes of radioactive nuclei, along with their characteristic nuclear decay reactions and the radiation they emit. As we shall see, nuclear decay reactions occur spontaneously under all conditions, but nuclear transmutation reactions occur only under very special conditions, such as the collision of a beam of highly energetic particles with a target nucleus or in the interior of stars. In contrast, in a nuclear transmutation reaction A nuclear reaction in which a nucleus reacts with a subatomic particle or another nuleus to give a product nucleus that is more massive than the starting material., a nucleus reacts with a subatomic particle or another nucleus to form a product nucleus that is more massive than the starting material. The resulting daughter nuclei have a lower mass and are lower in energy (more stable) than the parent nucleus that decayed. In a nuclear decay reaction A nuclear reaction that occurs when an unstable nucleus emits radiation and is transformed into the nucleus of one or more other elements., also called radioactive decay, an unstable nucleus emits radiation and is transformed into the nucleus of one or more other elements. The two general kinds of nuclear reactions are nuclear decay reactions and nuclear transmutation reactions. To know the different kinds of radioactive decay.The Auger effect bears some resemblance to internal conversion of the nucleus, which also ejects an electron. Though more involved in interpretation than optical spectra, the analysis of the energy spectrum of these emitted electrons does give information about the atomic energy levels. In other cases, the energy released by the downward transition is given to one of the outer electrons instead of to a photon, and this electron is then ejected from the atom with an energy equal to the energy lost by the electron which made the downward transition minus the binding energy of the electron that is ejected from the atom. ![]() This emission process for lighter atoms and outer electrons gives rise to line spectra. ![]() Since for heavy atoms this quantum energy will be in the x-ray region, it is commonly called x-ray fluorescence. Sometimes this transition will be accompanied by an emitted photon whose quantum energy matches the energy gap between the upper and lower level. ![]() If an inner shell electron is removed from an atom, an electron from a higher level will quickly make the transition downward to fill the vacancy. Taking as an example a transition that produced a Kα x-ray, the illustration at right shows the energy of the Kα x-ray photon divided between the kinetic energy of the Auger electron and an emitted photon after overcoming the electron binding energy U. The diagram of Auger electron emission above is over-simplified because the energy transferred to the outer electron to eject it would not in general be transferred entirely to that electron, but could also produce a photon along with the ejected electron. It is observed as one of the methods of electron rearrangement after electron capture into the nucleus. In Auger spectroscopy, the vacancy is produced by bombardment with high energy electrons, but the Auger effect can occur if the vacancy is produced by other interactions. The Auger effect is a process by which electrons with characteristic energies are ejected from atoms in response to a downward transition by another electron in the atom.
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