Misplaced Pages

Osmium (₇₆Os) has seven naturally occurring isotopes, five of which are stable: Os, Os, Os, Os, and (most abundant) Os. The other natural isotopes, Os, and Os, have extremely long half-life (1.12×10 years and 2×10 years, respectively) and for practical purposes can be considered to be stable as well. Os is the daughter of Re (half-life 4.12×10 years) and is most often measured in an Os/Os ratio. This ratio, as well as the Re/Os ratio, have been used extensively in dating terrestrial as well as meteoric rocks. It has also been used to measure the intensity of continental weathering over geologic time and to fix minimum ages for stabilization of the mantle roots of continental cratons. However, the most notable application of Os in dating has been in conjunction with iridium, to analyze the layer of shocked quartz along the Cretaceous–Paleogene boundary that marks the extinction of the dinosaurs 66 million years ago. Isotopically pure Os, were it available, would be the densest stable material on earth at 22.80 grams per cubic centimeter.

There are also 31 artificial radioisotopes, the longest-lived of which is Os with a half-life of six years; all others have half-lives under 93 days. There are also ten known nuclear isomers, the longest-lived of which is Os with a half-life of 13.10 hours. All isotopes and nuclear isomers of osmium are either radioactive or observationally stable, meaning that they are predicted to be radioactive but no actual decay has been observed.

Uses of osmium isotopes

The isotopic ratio of osmium-187 and osmium-188 (Os/Os) can be used as a window into geochemical changes throughout the ocean's history. The average marine Os/Os ratio in oceans is 1.06. This value represents a balance of the continental derived riverine inputs of Os with a Os/Os ratio of ~1.3, and the mantle/extraterrestrial inputs with a Os/Os ratio of ~0.13. Being a descendant of Re, Os can be radiogenically formed by beta decay. This decay has actually pushed the Os/Os ratio of the Bulk silicate earth (Earth minus the core) by 33%. This is what drives the difference in the Os/Os ratio we see between continental materials and mantle material. Crustal rocks have a much higher level of Re, which slowly degrades into Os driving up the ratio. Within the mantle however, the uneven response of Re and Os results in these mantle, and melted materials being depleted in Re, and do not allow for them to accumulate Os like the continental material. The input of both materials in the marine environment results in the observed Os/Os of the oceans and has fluctuated greatly over the history of our planet. These changes in the isotopic values of marine Os can be observed in the marine sediment that is deposited, and eventually lithified in that time period. This allows for researchers to make estimates on weathering fluxes, identifying flood basalt volcanism, and impact events that may have caused some of our largest mass extinctions. The marine sediment Os isotope record has been used to identify and corroborate the impact of the K-T boundary for example. The impact of this ~10 km asteroid massively altered the Os/Os signature of marine sediments at that time. With the average extraterrestrial Os/Os of ~0.13 and the huge amount of Os this impact contributed (equivalent to 600,000 years of present-day riverine inputs) lowered the global marine Os/Os value of ~0.45 to ~0.2.

Os isotope ratios may also be used as a signal of anthropogenic impact. The same Os/Os ratios that are common in geological settings may be used to gauge the addition of anthropogenic Os through things like catalytic converters. While catalytic converters have been shown to drastically reduce the emission of NO_x and CO, they are introducing platinum group elements (PGE) such as Os, to the environment. Other sources of anthropogenic Os include combustion of fossil fuels, smelting chromium ore, and smelting of some sulfide ores. In one study, the effect of automobile exhaust on the marine Os system was evaluated. Automobile exhaust Os/Os has been recorded to be ~0.2 (similar to extraterrestrial and mantle derived inputs) which is heavily depleted (3, 7). The effect of anthropogenic Os can be seen best by comparing aquatic Os ratios and local sediments or deeper waters. Impacted surface waters tend to have depleted values compared to deep ocean and sediments beyond the limit of what is expected from cosmic inputs. This increase in effect is thought to be due to the introduction of anthropogenic airborne Os into precipitation.

The long half-life of Os with respect to alpha decay to W has been proposed as a radiometric dating method for osmium-rich rocks or for differentiation of a planetary core.

List of isotopes

1. Os – 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. Bold half-life – nearly stable, half-life longer than age of universe.
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. # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
10. ^ primordial radionuclide
11. Theorized to also undergo ββ decay to W
12. ^ Used in rhenium-osmium dating
13. Believed to undergo α decay to W with a half-life over 3.2×10 years
14. Believed to undergo α decay to W with a half-life over 3.3×10 years
15. Believed to undergo α decay to W with a half-life over 3.3×10 years
16. Believed to undergo α decay to W with a half-life over 1.2×10 years
17. Believed to undergo α decay to W or ββ decay to Pt with a half-life over 5.3×10 years

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): 030001. doi:10.1088/1674-1137/abddae.
2. ^ Peters, Stefan T.M.; Münker, Carsten; Becker, Harry; Schulz, Toni (April 2014). "Alpha-decay of Os revealed by radiogenic W in meteorites: Half life determination and viability as geochronometer". Earth and Planetary Science Letters. 391: 69–76. doi:10.1016/j.epsl.2014.01.030.
3. "Standard Atomic Weights: Osmium". CIAAW. 1991.
4. 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.
5. Flegenheimer, Juan (2014). "The mystery of the disappearing isotope". Revista Virtual de Química. 6 (4): 1139–1142. doi:10.5935/1984-6835.20140073.
6. ^ Peucker-Ehrenbrink, B.; Ravizza, G. (2000). "The marine osmium isotope record". Terra Nova. 12 (5): 205–219. Bibcode:2000TeNov..12..205P. doi:10.1046/j.1365-3121.2000.00295.x. S2CID 12486288.
7. ^ Esser, Bradley K.; Turekian, Karl K. (1993). "The osmium isotopic composition of the continental crust". Geochimica et Cosmochimica Acta. 57 (13): 3093–3104. Bibcode:1993GeCoA..57.3093E. doi:10.1016/0016-7037(93)90296-9.
8. Hauri, Erik H. (2002). "Osmium Isotopes and Mantle Convection" (PDF). Philosophical Transactions: Mathematical, Physical and Engineering Sciences. 360 (1800): 2371–2382. Bibcode:2002RSPTA.360.2371H. doi:10.1098/rsta.2002.1073. JSTOR 3558902. PMID 12460472. S2CID 18451805.
9. Lowery, Christopher; Morgan, Joanna; Gulick, Sean; Bralower, Timothy; Christeson, Gail (2019). "Ocean Drilling Perspectives on Meteorite Impacts". Oceanography. 32: 120–134. doi:10.5670/oceanog.2019.133.
10. Selby, D.; Creaser, R. A. (2005). "Direct Radiometric Dating of Hydrocarbon Deposits Using Rhenium-Osmium Isotopes". Science. 308 (5726): 1293–1295. Bibcode:2005Sci...308.1293S. doi:10.1126/science.1111081. PMID 15919988. S2CID 41419594.
11. ^ Chen, C.; Sedwick, P. N.; Sharma, M. (2009). "Anthropogenic osmium in rain and snow reveals global-scale atmospheric contamination". Proceedings of the National Academy of Sciences. 106 (19): 7724–7728. Bibcode:2009PNAS..106.7724C. doi:10.1073/pnas.0811803106. PMC 2683094. PMID 19416862.
12. Cook, David L.; Kruijer, Thomas S.; Leya, Ingo; Kleine, Thorsten (September 2014). "Cosmogenic W variations in meteorites and re-assessment of a possible Os–W decay system". Geochimica et Cosmochimica Acta. 140: 160–176. doi:10.1016/j.gca.2014.05.013.
13. Cook, David L.; Smith, Thomas; Leya, Ingo; Hilton, Connor D.; Walker, Richard J.; Schönbächler, Maria (September 2018). "Excess W in IIAB iron meteorites: Identification of cosmogenic, radiogenic, and nucleosynthetic components". Earth Planet Sci Lett. 503: 29–36. doi:10.1016/j.epsl.2018.09.021. PMC 6398611.
14. 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.
15. ^ Briscoe, A. D.; Page, R. D.; Uusitalo, J.; et al. (2023). "Decay spectroscopy at the two-proton drip line: Radioactivity of the new nuclides Os and W". Physics Letters B. 47 (138310). doi:10.1016/j.physletb.2023.138310. hdl:10272/23933.

• 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.

v t e Isotopes of the chemical elements
Group 1 2   3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Period Hydrogen and alkali metals Alkaline earth metals Pnicto­gens Chal­co­gens Halo­gens Noble gases ① Isotopes § ListH1 Isotopes § ListHe2 ② Isotopes § ListLi3 Isotopes § ListBe4 Isotopes § ListB5 Isotopes § ListC6 Isotopes § ListN7 Isotopes § ListO8 Isotopes § ListF9 Isotopes § ListNe10 ③ Isotopes § ListNa11 Isotopes § ListMg12 Isotopes § ListAl13 Isotopes § ListSi14 Isotopes § ListP15 Isotopes § ListS16 Isotopes § ListCl17 Isotopes § ListAr18 ④ Isotopes § ListK19 Isotopes § ListCa20 Isotopes § ListSc21 Isotopes § ListTi22 Isotopes § ListV23 Isotopes § ListCr24 Isotopes § ListMn25 Isotopes § ListFe26 Isotopes § ListCo27 Isotopes § ListNi28 Isotopes § ListCu29 Isotopes § ListZn30 Isotopes § ListGa31 Isotopes § ListGe32 Isotopes § ListAs33 Isotopes § ListSe34 Isotopes § ListBr35 Isotopes § ListKr36 ⑤ Isotopes § ListRb37 Isotopes § ListSr38 Isotopes § ListY39 Isotopes § ListZr40 Isotopes § ListNb41 Isotopes § ListMo42 Isotopes § ListTc43 Isotopes § ListRu44 Isotopes § ListRh45 Isotopes § ListPd46 Isotopes § ListAg47 Isotopes § ListCd48 Isotopes § ListIn49 Isotopes § ListSn50 Isotopes § ListSb51 Isotopes § ListTe52 Isotopes § ListI53 Isotopes § ListXe54 ⑥ Isotopes § ListCs55 Isotopes § ListBa56 Isotopes § ListLu71 Isotopes § ListHf72 Isotopes § ListTa73 Isotopes § ListW74 Isotopes § ListRe75 Isotopes § ListOs76 Isotopes § ListIr77 Isotopes § ListPt78 Isotopes § ListAu79 Isotopes § ListHg80 Isotopes § ListTl81 Isotopes § ListPb82 Isotopes § ListBi83 Isotopes § ListPo84 Isotopes § ListAt85 Isotopes § ListRn86 ⑦ Isotopes § ListFr87 Isotopes § ListRa88 Isotopes § ListLr103 Isotopes § ListRf104 Isotopes § ListDb105 Isotopes § ListSg106 Isotopes § ListBh107 Isotopes § ListHs108 Isotopes § ListMt109 Isotopes § ListDs110 Isotopes § ListRg111 Isotopes § ListCn112 Isotopes § ListNh113 Isotopes § ListFl114 Isotopes § ListMc115 Isotopes § ListLv116 Isotopes § ListTs117 Isotopes § ListOg118 ⑧ Isotopes § ListUue119 Isotopes § ListUbn120 Isotopes § ListLa57 Isotopes § ListCe58 Isotopes § ListPr59 Isotopes § ListNd60 Isotopes § ListPm61 Isotopes § ListSm62 Isotopes § ListEu63 Isotopes § ListGd64 Isotopes § ListTb65 Isotopes § ListDy66 Isotopes § ListHo67 Isotopes § ListEr68 Isotopes § ListTm69 Isotopes § ListYb70   Isotopes § ListAc89 Isotopes § ListTh90 Isotopes § ListPa91 Isotopes § ListU92 Isotopes § ListNp93 Isotopes § ListPu94 Isotopes § ListAm95 Isotopes § ListCm96 Isotopes § ListBk97 Isotopes § ListCf98 Isotopes § ListEs99 Isotopes § ListFm100 Isotopes § ListMd101 Isotopes § ListNo102
Table of nuclides Categories: Isotopes Tables of nuclides Metastable isotopes Isotopes by element

• Isotopes of osmium
• Osmium
• Lists of isotopes by element