Gold-198

Last updated
Gold-198
Gold-198.svg
General
Symbol 198Au
Names gold-198
Protons (Z)79
Neutrons (N)119
Nuclide data
Half-life (t1/2)2.6946 d [1]
Isotope mass 197.9682437 [2] Da
Spin 2−
Decay products 198Hg
Decay modes
Decay mode Decay energy (MeV)
β− 1.373 [3]
Isotopes of gold
Complete table of nuclides

Gold-198 (198Au) is a radioactive isotope of gold, normally made by neutron capture on natural gold (entirely gold-197). It undergoes exclusively beta decay to stable 198 Hg with a half-life of 2.6946 days.

Contents

The decay properties of 198Au have led to interest in its potential use in radiotherapy for cancer treatments. This isotope has also found use in nuclear weapons research and as a radioactive tracer in hydrological research.

Discovery

198Au was possibly observed for the first time in 1935 by Enrico Fermi et al., though it was not correctly identified at the time. This isotope was conclusively identified in 1937 following neutron irradiation of stable 197Au and was ascribed a half-life of approximately 2.7 days. [4]

Decay

Decay scheme of Au to Hg Au198.svg
Decay scheme of Au to Hg

The decay of 198Au (shown) is relatively simple, involving only three levels of the daughter product nucleus. 99% of decaying atoms follow the path to the middle level, and thus emit a beta particle with maximum energy 961 keV (the rest goes to the neutrino) and a single gamma ray of energy 412 keV (converted about 4%). [3]

Applications

Nuclear medicine

198Au is used for radiotherapy in some cancer treatments. [5] [6] Its properties may be favorable for use in medicine because the 4  mm penetration range of its beta particles in tissue allows it to destroy tumors without nearby non-cancerous tissue being affected by radiation, [7] and its half-life is short but not so short as to create problems in handling or delivery. For this reason, 198Au nanoparticles are being investigated as an injectable treatment for prostate cancer. [7] [8]

Radioactive tracing

Sediment and water flow can be investigated using radioactive tracers such as 198Au. This has been used extensively since artificial radioisotopes became available in the 1950s, as a supplement to millennia of investigations using other tracing techniques. [9]

Inside coker units at oil refineries, 198Au is used to study the hydrodynamic behavior of solids in fluidized beds and can also be used to quantify the degree of fouling of bed internals. [10]

Nuclear weapons

Gold has been proposed as a material for creating a salted nuclear weapon (cobalt is another, better-known salting material). A jacket of natural 197
Au (the only stable gold isotope), irradiated by the intense neutron flux from an exploding thermonuclear weapon, would be transmuted into 198Au, whose gamma emission would significantly increase the radioactive hazard of the weapon's fallout for days. Such a weapon is not known to have ever been built, tested, or used. [11]

The highest amount of 198Au detected in any United States nuclear test was in shot "Sedan" detonated at Nevada Test Site on July 6, 1962. [12]

See also

References

  1. ↑ Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 139. doi:10.1088/1674-1137/abddae.
  2. ↑ Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.
  3. 1 2 National Nuclear Data Center. "NuDat 3.0 database". Brookhaven National Laboratory.
  4. ↑ Schuh, A.; Fritsch, A.; Ginepro, J.Q.; Heim, M.; Shore, A.; Thoennessen, M. (2010). "Discovery of the gold isotopes" (PDF). Atomic Data and Nuclear Data Tables . 96 (3): 307–314. arXiv: 0903.1797 . Bibcode:2010ADNDT..96..307S. doi:10.1016/j.adt.2009.12.001. S2CID   98691829.
  5. ↑ "Nanoscience and Nanotechnology in Nanomedicine: Hybrid Nanoparticles In Imaging and Therapy of Prostate Cancer". Radiopharmaceutical Sciences Institute, University of Missouri-Columbia. Archived from the original on March 14, 2009.
  6. ↑ Hainfeld, James F.; Dilmanian, F. Avraham; Slatkin, Daniel N.; Smilowitz, Henry M. (2008). "Radiotherapy enhancement with gold nanoparticles". Journal of Pharmacy and Pharmacology. 60 (8): 977–85. doi: 10.1211/jpp.60.8.0005 . PMID   18644191. S2CID   32861131.
  7. 1 2 Katti, K.V.; Khoobchandanai, M.; Al-Yasiri, A.; Katti, K.K.; Cutler, C.; Loyalka, S.K. (2017). Radioactive Gold-198 Nanoparticles In Nanomedicine: Green Nanotechnology and Radiochemical Approaches in Oncology. 6th Asia-Pacific Symposium on Radiochemistry. Jeju.
  8. ↑ "Green Tea and Gold Nanoparticles Destroy Prostate Tumors". 2012.
  9. ↑ Plata-Bedmar, A. (1988). Artificial radioisotopes in hydrological investigation: A review of specific applications (PDF) (Report). Topical reports. IAEA Bulletin. pp. 35–38.
  10. ↑ Sanchez, Francisco J.; Granovskiy, Mikhail (2012). "Application of radioactive particle tracking to indicate shed fouling in the stripper section of a fluid coker". Canadian Journal of Chemical Engineering. 91 (6): 1175–1182. doi:10.1002/cjce.21740.
  11. ↑ D. T. Win; M. Al Masum (2003). "Weapons of Mass Destruction" (PDF). Assumption University Journal of Technology. 6 (4): 199–219. Archived from the original on 2009-03-26. Retrieved 2024-04-28.{{cite journal}}: CS1 maint: bot: original URL status unknown (link)
  12. ↑ R. L. Miller (2002). U.S. Atlas of Nuclear Fallout, 1951–1970. Vol. 1 (Abridged General Reader ed.). Two Sixty Press. p. 340. ISBN   978-1-881043-13-3.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.