![]() ![]() Since the internal conversion process can interact with any of the orbital electrons, the result is a spectrum of internal conversion electrons which will be seen as superimposed upon the electron energy spectrum of the beta emission. In this case the internal conversion is more probable. It can proceed to the ground state by emitting a 279.190 keV gamma ray, or by internal conversion. It is also not the same as beta decay, since the emitted electron was previously one of the orbital electrons, whereas the electron in beta decay is produced by the decay of a neutron.Īn example used by Krane is that of 203Hg, which decays to 203Tl by beta emission, leaving the 203Tl in an electromagnetically excited state. This process is not the same as emitting a gamma ray which knocks an electron out of the atom. Sometimes the multipole electric fields of the nucleus interact with orbital electrons with enough energy to eject them from the atom. Internal conversion is another electromagnetic process which can occur in the nucleus and which competes with gamma emission. An example of this pattern is seen with silver isotopes, with two stable isotopes plus one of lower mass which decays by electron capture and one of heavier mass which decays by beta emission.Īn important example of electron capture decay is that of potassium-40 since it forms the basis for the potassium-argon mineral dating process. In the middle range of the periodic table, those isotopes which are lighter than the most stable isotopes tend to decay by electron capture, and those heavier decay by negative beta decay. The process leaves a vacancy in the electron energy level from which the electron came, and that vacancy is either filled by the dropping down of a higher-level electron with the emission of an X-ray or by the ejection of an outer electron in a process called the Auger effect.Įlectron capture is a process which involves the weak interaction and can be represented by a Feynman diagram. ![]() The capture of the electron by a proton in the nucleus is accompanied by the emission of a neutrino. The electron orbit radii are tens of thousands of times the diameter of the nucleus.Ī typical example is the decay of beryllium 7 4 Be + 0 -1 e → 7 3 Li + ν This is a schematic that grossly distorts the picture relative to a scale model of the atom. Most commonly, it is a K-shell electron which is captured, and this is referred to as K-capture. This is a process which competes with positron emission and has the same effect on the atomic number. ![]() A parent nucleus may capture one of its orbital electrons and emit a neutrino. Internal conversion is the use of electromagnetic energy from the nucleus to expel an orbital electron from the atom.Įlectron capture is one form of radioactivity. They both show a characteristic energy spectrum because of the emission of a neutrino or antineutrino. Positron or positive beta decay: Positron emission is called beta decay because the characteristics of electron or positron decay are similar. ![]() This is exhibited in the potassium-argon decay. While the most common types of radioactive decay are by alpha, beta, and gamma radiation, several other varieties of radioactivity occur:Įlectron capture: A parent nucleus may capture one of its own electrons and emit a neutrino. Gamma radiation is the most useful type of radiation for medical purposes, but at the same time it is the most dangerous because of its ability to penetrate large thicknesses of material. Most gamma rays are somewhat higher in energy than x-rays and therefore are very penetrating. It is distinguished from x-rays only by the fact that it comes from the nucleus. Gamma radioactivity is composed of electromagnetic rays. ![]()
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