Search results
Results from the WOW.Com Content Network
This chain of decay was later shown to have the mass number 99, and (...) the 6.6-h activity acquired the designation ‘technetium-99m. Later in 1940, Emilio Segrè and Chien-Shiung Wu published experimental results of an analysis of fission products of uranium-235, including molybdenum-99, and detected the presence of an isomer of element 43 ...
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.
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.
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 Bateman equation predicts the relative quantities of all the isotopes that compose a given decay chain once that decay chain has proceeded long enough for some of its daughter products to have reached the stable (i.e., nonradioactive) end of the chain. A decay chain that has reached this state, which may require billions of years, is said ...
Molybdenum-99 is produced commercially by intense neutron-bombardment of a highly purified uranium-235 target, followed rapidly by extraction. [8] It is used as a parent radioisotope in technetium-99m generators to produce the even shorter-lived daughter isotope technetium-99m, which is used in approximately 40 million medical procedures annually.
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.
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.