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The metastable technetium-99m (99m Tc) is a short-lived (half-life about 6 hours) nuclear isomer used in nuclear medicine, produced from molybdenum-99. It decays by isomeric transition to technetium-99, a desirable characteristic, since the very long half-life and type of decay of technetium-99 imposes little further radiation burden on the body.
Technetium-99m was discovered as a product of cyclotron bombardment of molybdenum. This procedure produced molybdenum-99, a radionuclide with a longer half-life (2.75 days), which decays to 99m Tc. This longer decay time allows for 99 Mo to be shipped to medical facilities, where 99m Tc is extracted from
For technetium-98 and heavier isotopes, the primary mode is beta emission (the emission of an electron or positron), producing ruthenium (Z = 44), with the exception that technetium-100 can decay both by beta emission and electron capture. [59] [60] Technetium also has numerous nuclear isomers, which are isotopes with one or more excited nucleons.
Beta decay of fission products of mass 95–98 stops at the stable isotopes of molybdenum of those masses and does not reach technetium. For mass 100 and greater, the technetium isotopes of those masses are very short-lived and quickly beta decay to isotopes of ruthenium. Therefore, the technetium in spent nuclear fuel is practically all 99 Tc.
It is also produced (via the short lived nuclear isomer Technetium-99m) as a decay product of Molybdenum-99. Technetium is particularly mobile in the environment as it forms negatively charged pertechnetate-ions and it presents the biggest radiological hazard among the long lived fission products. Despite being a metal, Technetium usually doesn ...
Five modern technetium-99m generators The first technetium-99m generator, unshielded, 1958. A Tc-99m pertechnetate solution is being eluted from Mo-99 molybdate bound to a chromatographic substrate A technetium-99m generator , or colloquially a technetium cow or moly cow , is a device used to extract the metastable isotope 99m Tc of technetium ...
The first, technetium, was created in 1937. [3] Plutonium (Pu, atomic number 94), first synthesized in 1940, is another such element. It is the element with the largest number of protons (atomic number) to occur in nature, but it does so in such tiny quantities that it is far more practical to synthesize it.
The primary decay product before 102 Ru is technetium and the primary product after is rhodium. Because of the very high volatility of ruthenium tetroxide ( RuO 4 ) ruthenium radioactive isotopes with their relative short half-life are considered as the second most hazardous gaseous isotopes after iodine-131 in case of release by a nuclear ...