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Isotopes of gold

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Isotopes of gold (79Au)
Main isotopes[1] Decay
Isotope abun­dance half-life (t1/2) mode pro­duct
195Au synth 186.01 d ε 195Pt
196Au synth 6.165 d β+ 196Pt
β− 196Hg
197Au 100% stable
198Au synth 2.6946 d β− 198Hg
199Au synth 3.139 d β− 199Hg
Standard atomic weight Ar°(Au)

Gold (79Au) has one stable isotope, 197Au, and known radioisotopes ranging from 169Au to 210Au, with 195Au being the most stable with a half-life of 186.01 days, followed by 196Au at 6.165 days. Isotopes heavier than the stable mass number 197 generally decay by beta emission to mercury isotopes, while those lighter decay by electron capture to platinum isotopes or alpha emission to iridium isotopes; 196 decays both to platinum and to mercury. Of the meta states the most stable is 198m2Au at 2.27 days.

Gold is currently the heaviest monoisotopic element (and is also mononuclidic). Bismuth formerly held that distinction until alpha decay of the 209Bi isotope was observed. All isotopes of gold are either radioactive or, in the case of 197Au, observationally stable, meaning that 197Au is predicted to be radioactive but no actual decay has been observed.[4]

List of isotopes

[edit]


Nuclide
[n 1]		 Z N Isotopic mass (Da)[5]
[n 2][n 3]		 Discovery
year[6][7]		 Half-life[1]
[n 4]		 Decay
mode[1]
[n 5]		 Daughter
isotope
[n 6][n 7]		 Spin and
parity[1]
[n 8][n 4]		 Isotopic
abundance
Excitation energy[n 4]
169Au[8] 79 90 168.99808(32)# (2000) 1.16+0.50
−0.47 μs		 p (~94%) 168Pt (11/2−)
α (~6%) 165mIr
170Au[9] 79 91 169.99602(22)# 2004 286+50
−40 μs		 p (89%) 169Pt (2)−
α (11%) 166Ir
170mAu[9] 282(10) keV 2004 617+50
−40 μs		 p (58%) 169Pt (9)+
α (42%) 166mIr
171Au[9] 79 92 170.991882(22) 1997 22+3
−2 μs		 p 170Pt 1/2+
α? 167Ir
171mAu[9] 258(13) keV 1999 1.09(3) ms α (66%) 167mIr 11/2−
p (34%) 170Pt
172Au 79 93 171.99000(6) 1993 28(4) ms α (98%) 168Ir (2)−
p (2%) 171Pt
β+ 172Pt
172mAu[n 9] 160(250) keV 2009 11.0(10) ms α 168Ir (9,10)+
p? 171Pt
173Au 79 94 172.986224(24) 1983 25.5(8) ms α (86%) 169Ir (1/2+)
β+ (14%) 173Pt
173mAu 214(21) keV 1999 12.2(1) ms α (89%) 169Ir (11/2−)
β+ (11%) 173Pt
174Au 79 95 173.98491(11)# 1983 139(3) ms α (90%) 170Ir (3−)
β+ (10%) 174Pt
174mAu 130(50)# keV (2004)[n 10] 162(2) ms α? 170Ir (9+)
β+? 174Pt
175Au 79 96 174.98132(4) 1975 200(3) ms α (88%) 171Ir 1/2+
β+ (12%) 175Pt
175mAu 164(11)# keV 2013 136(1) ms α (75%) 171Ir (11/2−)
β+ (25%) 175Pt
176Au 79 97 175.98012(4) 1975 1.05(1) s α (75%) 172Ir (3−,4−)
β+ (25%) 176Pt
176mAu[n 9] 139(13) keV 2014 1.36(2) s α? 172Ir (8+,9+)
β+? 176Pt
177Au 79 98 176.976870(11) 1968 1.501(20) s β+ (60%) 177Pt 1/2+
α (40%) 173Ir
177mAu 190(7) keV 2001 1.193(13) s α (60%) 173Ir 11/2−
β+ (40%) 177Pt
178Au 79 99 177.976057(11) 1968 3.4(5) s β+ (84%) 178Pt (2+,3−)
α (16%) 174Ir
178m1Au 50.3(2) keV 2021 300(10) ns IT 178Au (4−,5+)
178m2Au 186(14) keV 2020 2.7(5) s β+ (82%) 178Pt (7+,8−)
α (18%) 174Ir
178m3Au 243(14) keV 2021 390(10) ns IT 178Au (5+,6)
179Au 79 100 178.973174(13) 1968 7.1(3) s β+ (78.0%) 179Pt 1/2+
α (22.0%) 175Ir
179mAu 89.5(3) keV 2011 327(5) ns IT 179Au (3/2−)
180Au 79 101 179.9724898(51) 1977 7.9(3) s β+ (99.42%) 180Pt (1+)
α (0.58%) 176Ir
181Au 79 102 180.970079(21) 1968 13.7(14) s β+ (97.3%) 181Pt (5/2−)
α (2.7%) 177Ir
182Au 79 103 181.969614(20) 1970 15.5(4) s β+ (99.87%) 182Pt (2+)
α (0.13%) 178Ir
183Au 79 104 182.967588(10) 1968 42.8(10) s β+ (99.45%) 183Pt 5/2−
α (0.55%) 179Ir
183mAu 73.10(1) keV 1984 >1 μs IT 183Au (1/2)+
184Au 79 105 183.967452(24) 1969 20.6(9) s β+ (99.99%) 184Pt 5+
α (0.013%) 180Ir
184mAu 68.46(4) keV 1997 47.6(14) s β+ (70%) 184Pt 2+
IT (30%) 184Au
α (0.013%) 180Ir
185Au 79 106 184.9657989(28) 1960 4.25(6) min β+ (99.74%) 185Pt 5/2−
α (0.26%) 181Ir
185mAu[n 9] 50(50)# keV 1968 6.8(3) min β+ 185Pt 1/2+#
IT? 185Au
186Au 79 107 185.965953(23) 1960 10.7(5) min β+ 186Pt 3−
α (8×10−4%) 182Ir
186mAu 227.77(7) keV 1985 110(10) ns IT 186Au 2+
187Au 79 108 186.964542(24) 1955 8.3(2) min β+ 187Pt 1/2+
α? 183Ir
187mAu 120.33(14) keV 1983 2.3(1) s IT 187Au 9/2−
188Au 79 109 187.9652480(29) 1955 8.84(6) min β+ 188Pt 1−
189Au 79 110 188.963948(22) 1955 28.7(4) min β+ 189Pt 1/2+
α? (<3×10−5%) 185Ir
189m1Au 247.25(16) keV 1966 4.59(11) min β+ 189Pt 11/2−
IT? 189Au
189m2Au 325.12(16) keV 1975 190(15) ns IT 189Au 9/2−
189m3Au 2554.8(8) keV 1975 242(10) ns IT 189Au 31/2+
190Au 79 111 189.964752(4) 1959 42.8(10) min β+ 190Pt 1−
α? (<10−6%) 186Ir
190mAu[n 9] 200(150)# keV 1982 125(20) ms IT 190Au 11−#
β+? 190Pt
191Au 79 112 190.963716(5) 1954 3.18(8) h β+ 191Pt 3/2+
191m1Au 266.2(7) keV 1971 920(110) ms IT 191Au 11/2−
191m2Au 2489.6(9) keV 1985 402(20) ns IT 191Au 31/2+
192Au 79 113 191.964818(17) 1948 4.94(9) h β+ 192Pt 1−
192m1Au 135.41(25) keV 1982 29 ms IT 192Au 5+
192m2Au 431.6(5) keV 1982 160(20) ms IT 192Au 11−
193Au 79 114 192.964138(9) 1948 17.65(15) h β+ 193Pt 3/2+
193m1Au 290.20(4) keV 1954 3.9(3) s IT (99.97%) 193Au 11/2−
β+ (0.03%) 193Pt
193m2Au 2486.7(6) keV 1979 150(50) ns IT 193Au 31/2+
194Au 79 115 193.9654191(23) 1948 38.02(10) h β+ 194Pt 1−
194m1Au 107.4(5) keV 1975 600(8) ms IT 194Au 5+
194m2Au 475.8(6) keV 1975 420(10) ms IT 194Au 11−
195Au 79 116 194.9650378(12) 1948 186.01(6) d EC 195Pt 3/2+
195m1Au 318.58(4) keV 1955 30.5(2) s IT 195Au 11/2−
195m2Au 2501(20)# keV 2013 12.89(21) μs IT 195Au 31/2(−)
196Au 79 117 195.966571(3) 1937 6.165(11) d β+ (93.0%) 196Pt 2−
β− (7.0%) 196Hg
196m1Au 84.656(20) keV 1971 8.1(2) s IT 196Au 5+
196m2Au 595.66(4) keV 1937 9.603(22) h IT 196Au 12−
197Au[n 11] 79 118 196.9665701(6) 1935 Observationally Stable[n 12] 3/2+ 1.0000
197m1Au 409.15(8) keV 1945 7.73(6) s IT 197Au 11/2−
197m2Au 2532.5(10) keV 2006 150(5) ns IT 197Au 27/2+#
198Au 79 119 197.9682437(6) 1937 2.69464(14) d β− 198Hg 2−
198m1Au 312.2227(20) keV 1968 124(4) ns IT 198Au 5+
198m2Au 811.9(15) keV 1972 2.272(16) d IT 198Au 12−
199Au 79 120 198.9687666(6) 1937 3.139(7) d β− 199Hg 3/2+
199mAu 548.9405(21) keV 1968 440(30) μs IT 199Au 11/2−
200Au 79 121 199.970757(29) 1951 48.4(3) min β− 200Hg (1−)
200mAu 1010(40) keV 1968 18.7(5) h β− (84%) 200Hg 12−
IT (16%) 200Au
201Au 79 122 200.971658(3) 1952 26.0(8) min β− 201Hg 3/2+
201m1Au 594(5) keV 2011 730(630) μs IT 201Au 11/2-
201m2Au 1610(5) keV 2011 5.6(24) μs IT 201Au 19/2+#
202Au 79 123 201.973856(25) 1967 28.4(12) s β− 202Hg (1−)
203Au 79 124 202.9751545(33) 1952 60(6) s β− 203Hg 3/2+
203mAu 641(3) keV 2005 140(44) μs IT 203Au 11/2−#
204Au 79 125 203.97811(22)# 1972 38.3(13) s β− 204Hg (2−)
204mAu 3816(500)# keV 2011 2.1(3) μs IT 204Au 16+#
205Au 79 126 204.98006(22)# 1994 32.0(14) s β− 205Hg 3/2+#
205m1Au 907(5) keV 2009 6(2) s IT? 205Au 11/2−#
β−? 205Hg
205m2Au 2849.7(4) keV 2011 163(5) ns IT 205Au 19/2+#
206Au 79 127 205.98477(32)# 2011 47(11) s β− 206Hg 6+#
207Au 79 128 206.98858(32)# 2010 3# s
[>300 ns]		 β−? 207Hg 3/2+#
β−, n? 206Hg
208Au 79 129 207.99366(32)# 2010 20# s
[>300 ns]		 β−? 208Hg 6+#
β−, n? 207Hg
209Au 79 130 208.99761(43)# 2010 1# s
[>300 ns]		 β−? 209Hg 3/2+#
β−, n? 208Hg
210Au 79 131 210.00288(43)# 2010 10# s
[>300 ns]		 β−? 210Hg 6+#
β−, n? 209Hg
This table header & footer:
  1. ↑ mAu – Excited nuclear isomer.
  2. ↑ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  3. ↑ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
  4. 1 2 3 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  5. ↑ Modes of decay:
    EC:Electron capture
    IT:Isomeric transition
    p:Proton emission
  6. ↑ Bold italics symbol as daughter – Daughter product is nearly stable.
  7. ↑ Bold symbol as daughter – Daughter product is stable.
  8. ↑ ( ) spin value – Indicates spin with weak assignment arguments.
  9. 1 2 3 4 Order of ground state and isomer is uncertain.
  10. ↑ Only published in a conference proceeding and not a refereed journal
  11. ↑ Potential material for salted bombs
  12. ↑ Theoretically predicted to undergo α decay to 193Ir

Gold-198

[edit]
Decay scheme of 198Au to 198Hg

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 198Hg with a half-life of 2.6946 days. 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%).[10]

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.[11]

Applications

[edit]

198Au is used for radiotherapy in some cancer treatments.[12][13] 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,[14] 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.[14][15]

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.[16]

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.[17]

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 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.[18] However, 198
Au was created during the SL-1 accident in 1961 when the reactor went prompt critical, causing 197
Au in a reactor operator's wedding ring to transmute into 198
Au.[19] 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.[20]

See also

[edit]

Daughter products other than gold

References

[edit]
  1. 1 2 3 4 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) 030001. doi:10.1088/1674-1137/abddae.
  2. ↑ "Standard Atomic Weights: Gold". CIAAW. 2017.
  3. ↑ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
  4. ↑ Belli, P.; Bernabei, R.; Danevich, F. A.; et al. (2019). "Experimental searches for rare alpha and beta decays". European Physical Journal A. 55 (8): 140–1–140–7. arXiv:1908.11458. Bibcode:2019EPJA...55..140B. doi:10.1140/epja/i2019-12823-2. ISSN 1434-601X. S2CID 201664098.
  5. ↑ 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.
  6. ↑ FRIB Nuclear Data Group. "Discovery of Nuclides Project, Isotope Database". doi:10.11578/frib/2279152.
  7. ↑ FRIB Nuclear Data Group. "Discovery of Nuclides Project, Isomer Database". doi:10.11578/frib/2572219.
  8. ↑ Uusitalo, J; Saren, J; Partanen, J; Hilton, J. "Mass Analyzing Recoil Apparatus MARA".
  9. 1 2 3 4 Kettunen, H.; Enqvist, T.; Grahn, T.; Greenlees, P. T.; Jones, P.; Julin, R.; Juutinen, S.; Keenan, A.; Kuusiniemi, P.; Leino, M.; Leppänen, A.-P.; Nieminen, P.; Pakarinen, J.; Rahkila, P.; Uusitalo, J. (28 May 2004). "Decay studies of Au 170, 171, Hg 171 – 173, and Tl 176". Physical Review C. 69 (5) 054323. doi:10.1103/PhysRevC.69.054323. ISSN 0556-2813. Retrieved 11 June 2023.
  10. ↑ National Nuclear Data Center. "NuDat 3.0 database". Brookhaven National Laboratory.
  11. ↑ 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.
  12. ↑ "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.
  13. ↑ 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.
  14. 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.
  15. ↑ "Green Tea and Gold Nanoparticles Destroy Prostate Tumors". 2012.
  16. ↑ Plata-Bedmar, A. (1988). Artificial radioisotopes in hydrological investigation: A review of specific applications (PDF) (Report). Topical reports. IAEA Bulletin. pp. 35–38.
  17. ↑ 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.
  18. ↑ 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)
  19. ↑ "SL-1 Reactor Accident on January 3, 1961, Interim Report," May 15, 1961, IDO-19300, CEND-128, Combustion Engineering, Inc., Nuclear Division, Windsor, Connecticut.
  20. ↑ 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.
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