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Isotopes of niobium

Naturally occurring niobium (₄₁Nb) is composed of one stable isotope (⁹³Nb). The most stable radioisotopeis⁹²Nb with a half-life of 34.7 million years. The next longest-lived niobium isotopes are ⁹⁴Nb (half-life: 20,300 years) and ⁹¹Nb with a half-life of 680 years. There is also a meta stateof⁹³Nb at 31 keV whose half-life is 16.13 years. Twenty-seven other radioisotopes have been characterized. Most of these have half-lives that are less than two hours, except ⁹⁵Nb (35 days), ⁹⁶Nb (23.4 hours) and ⁹⁰Nb (14.6 hours). The primary decay mode before stable ⁹³Nb is electron capture and the primary mode after is beta emission with some neutron emission occurring in ^104–110Nb.

Only ⁹⁵Nb (35 days) and ⁹⁷Nb (72 minutes) and heavier isotopes (half-lives in seconds) are fission products in significant quantity, as the other isotopes are shadowed by stable or very long-lived (⁹³Zr) isotopes of the preceding element zirconium from production via beta decay of neutron-rich fission fragments. ⁹⁵Nb is the decay productof⁹⁵Zr (64 days), so disappearance of ⁹⁵Nb in used nuclear fuel is slower than would be expected from its own 35-day half-life alone. Small amounts of other isotopes may be produced as direct fission products.

List of isotopes[edit]

Niobium-92[edit]

Niobium-92 is an extinct radionuclide^[7] with a half-life of 34.7 million years, decaying predominantly via β⁺ decay. Its abundance relative to the stable ⁹³Nb in the early Solar System, estimated at 1.7×10⁻⁵, has been measured to investigate the origin of p-nuclei.^[7][8] A higher initial abundance of ⁹²Nb has been estimated for material in the outer protosolar disk (sampled from the meteorite NWA 6704), suggesting that this nuclide was predominantly formed via the gamma process (photodisintegration) in a nearby core-collapse supernova.^[9]

Niobium-92, along with niobium-94, has been detected in refined samples of terrestrial niobium and may originate from bombardment by cosmic ray muons in Earth's crust.^[10]

References[edit]

• Isotope masses from:
  • Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
• Isotopic compositions and standard atomic masses from:
  • de Laeter, John Robert; Böhlke, John Karl; De Bièvre, Paul; Hidaka, Hiroshi; Peiser, H. Steffen; Rosman, Kevin J. R.; Taylor, Philip D. P. (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
  • Wieser, Michael E. (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051.
• "News & Notices: Standard Atomic Weights Revised". International Union of Pure and Applied Chemistry. 19 October 2005.
• Half-life, spin, and isomer data selected from the following sources.
  • Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
  • National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
  • Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.