Isotopes of osmium

Isotopes of osmium (₇₆Os)
Standard atomic weight Ar°(Os)
	190.23±0.03; 190.23±0.03 (abridged);
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Osmium (₇₆Os) has seven naturally occurring isotopes, 6 of which are stable: ¹⁸⁴Os, ¹⁸⁷Os, ¹⁸⁸Os, ¹⁸⁹Os, ¹⁹⁰Os, and (most abundant) ¹⁹²Os. The other natural isotope, ¹⁸⁶Os, has an extremely long half-life (2×10¹⁵ years) and for practical purposes can be considered to be stable as well. ¹⁸⁷Os is the daughter of ¹⁸⁷Re (half-life 4.56×10¹⁰ years) and is most often measured in an ¹⁸⁷Os/¹⁸⁸Os ratio. This ratio, as well as the ¹⁸⁷Re/¹⁸⁸Os 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.

There are also 30 artificial radioisotopes,^[5] the longest-lived of which is ¹⁹⁴Os with a half-life of 6 years, all others have half-lives under 94 days. There are also 9 known nuclear isomers, the longest-lived of which is ^191mOs with a half-life of 13.10 hours.

List of isotopes

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life^{[n 1]}	decay mode(s)^[6]^{[n 2]}	daughter isotope(s)^{[n 3]}	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
nuclide symbol	excitation energy			half-life^{[n 1]}	decay mode(s)^[6]^{[n 2]}	daughter isotope(s)^{[n 3]}	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
¹⁶¹Os	76	85		0.64(6) ms	α	¹⁵⁷W
¹⁶²Os	76	86	161.98443(54)#	1.87(18) ms	α	¹⁵⁸W	0+
¹⁶³Os	76	87	162.98269(43)#	5.5(6) ms	α	¹⁵⁹W	7/2−#
					β⁺, p (rare)	¹⁶²W
					β⁺ (rare)	¹⁶³Re
¹⁶⁴Os	76	88	163.97804(22)	21(1) ms	α (98%)	¹⁶⁰W	0+
¹⁶⁴Os	76	88	163.97804(22)	21(1) ms	β⁺ (2%)	¹⁶⁴Re	0+
¹⁶⁵Os	76	89	164.97676(22)#	71(3) ms	α (60%)	¹⁶¹W	(7/2−)
¹⁶⁵Os	76	89	164.97676(22)#	71(3) ms	β⁺ (40%)	¹⁶⁵Re	(7/2−)
¹⁶⁶Os	76	90	165.972691(20)	216(9) ms	α (72%)	¹⁶²W	0+
¹⁶⁶Os	76	90	165.972691(20)	216(9) ms	β⁺ (28%)	¹⁶⁶Re	0+
¹⁶⁷Os	76	91	166.97155(8)	810(60) ms	α (67%)	¹⁶³W	3/2−#
¹⁶⁷Os	76	91	166.97155(8)	810(60) ms	β⁺ (33%)	¹⁶⁷Re	3/2−#
¹⁶⁸Os	76	92	167.967804(13)	2.06(6) s	β⁺ (51%)	¹⁶⁸Re	0+
¹⁶⁸Os	76	92	167.967804(13)	2.06(6) s	α (49%)	¹⁶⁴W	0+
¹⁶⁹Os	76	93	168.967019(27)	3.40(9) s	β⁺ (89%)	¹⁶⁹Re	3/2−#
¹⁶⁹Os	76	93	168.967019(27)	3.40(9) s	α (11%)	¹⁶⁵W	3/2−#
¹⁷⁰Os	76	94	169.963577(12)	7.46(23) s	β⁺ (91.4%)	¹⁷⁰Re	0+
¹⁷⁰Os	76	94	169.963577(12)	7.46(23) s	α (8.6%)	¹⁷⁶W	0+
¹⁷¹Os	76	95	170.963185(20)	8.3(2) s	β⁺ (98.3%)	¹⁷¹Re	(5/2−)
¹⁷¹Os	76	95	170.963185(20)	8.3(2) s	α (1.7%)	¹⁶⁷W	(5/2−)
¹⁷²Os	76	96	171.960023(16)	19.2(5) s	β⁺ (98.9%)	¹⁷²Re	0+
¹⁷²Os	76	96	171.960023(16)	19.2(5) s	α (1.1%)	¹⁶⁸W	0+
¹⁷³Os	76	97	172.959808(16)	22.4(9) s	β⁺ (99.6%)	¹⁷³Re	(5/2−)
¹⁷³Os	76	97	172.959808(16)	22.4(9) s	α (.4%)	¹⁶⁹W	(5/2−)
¹⁷⁴Os	76	98	173.957062(12)	44(4) s	β⁺ (99.97%)	¹⁷⁴Re	0+
¹⁷⁴Os	76	98	173.957062(12)	44(4) s	α (.024%)	¹⁷⁰W	0+
¹⁷⁵Os	76	99	174.956946(15)	1.4(1) min	β⁺	¹⁷⁵Re	(5/2−)
¹⁷⁶Os	76	100	175.95481(3)	3.6(5) min	β⁺	¹⁷⁶Re	0+
¹⁷⁷Os	76	101	176.954965(17)	3.0(2) min	β⁺	¹⁷⁷Re	1/2−
¹⁷⁸Os	76	102	177.953251(18)	5.0(4) min	β⁺	¹⁷⁸Re	0+
¹⁷⁹Os	76	103	178.953816(19)	6.5(3) min	β⁺	¹⁷⁹Re	(1/2−)
¹⁸⁰Os	76	104	179.952379(22)	21.5(4) min	β⁺	¹⁸⁰Re	0+
¹⁸¹Os	76	105	180.95324(3)	105(3) min	β⁺	¹⁸¹Re	1/2−
^181m1Os	48.9(2) keV			2.7(1) min	β⁺	¹⁸¹Re	(7/2)−
^181m2Os	156.5(7) keV			316(18) ns			(9/2)+
¹⁸²Os	76	106	181.952110(23)	22.10(25) h	EC	¹⁸²Re	0+
¹⁸³Os	76	107	182.95313(5)	13.0(5) h	β⁺	¹⁸³Re	9/2+
^183mOs	170.71(5) keV			9.9(3) h	β⁺ (85%)	¹⁸³Re	1/2−
^183mOs	170.71(5) keV			9.9(3) h	IT (15%)	¹⁸³Os	1/2−
¹⁸⁴Os	76	108	183.9524891(14)	Observationally Stable^{[n 4]}			0+	2(1)×10⁻⁴
¹⁸⁵Os	76	109	184.9540423(14)	93.6(5) d	EC	¹⁸⁵Re	1/2−
^185m1Os	102.3(7) keV			3.0(4) µs			(7/2−)#
^185m2Os	275.7(8) keV			0.78(5) µs			(11/2+)
¹⁸⁶Os^{[n 5]}	76	110	185.9538382(15)	2.0(11)×10¹⁵ y	α	¹⁸²W	0+	0.0159(3)
¹⁸⁷Os^{[n 6]}	76	111	186.9557505(15)	Observationally Stable^{[n 7]}			1/2−	0.0196(2)
¹⁸⁸Os^{[n 6]}	76	112	187.9558382(15)	Observationally Stable^{[n 8]}			0+	0.1324(8)
¹⁸⁹Os	76	113	188.9581475(16)	Observationally Stable^{[n 9]}			3/2−	0.1615(5)
^189mOs	30.812(15) keV			5.81(6) h	IT	¹⁸⁹Os	9/2−
¹⁹⁰Os	76	114	189.9584470(16)	Observationally Stable^{[n 10]}			0+	0.2626(2)
^190mOs	1705.4(2) keV			9.9(1) min	IT	¹⁹⁰Os	(10)−
¹⁹¹Os	76	115	190.9609297(16)	15.4(1) d	β⁻	¹⁹¹Ir	9/2−
^191mOs	74.382(3) keV			13.10(5) h	IT	¹⁹¹Os	3/2−
¹⁹²Os	76	116	191.9614807(27)	Observationally Stable^{[n 11]}			0+	0.4078(19)
^192mOs	2015.40(11) keV			5.9(1) s	IT (87%)	¹⁹²Os	(10−)
^192mOs	2015.40(11) keV			5.9(1) s	β⁻ (13%)	¹⁹²Ir	(10−)
¹⁹³Os	76	117	192.9641516(27)	30.11(1) h	β⁻	¹⁹³Ir	3/2−
¹⁹⁴Os	76	118	193.9651821(28)	6.0(2) y	β⁻	¹⁹⁴Ir	0+
¹⁹⁵Os	76	119	194.96813(54)	6.5 min	β⁻	¹⁹⁵Ir	3/2−#
¹⁹⁶Os	76	120	195.96964(4)	34.9(2) min	β⁻	¹⁹⁶Ir	0+
¹⁹⁷Os	76	121		2.8(6) min

^ Bold for isotopes with half-lives longer than the age of the universe (nearly stable)
^ Abbreviations:
EC: Electron capture
IT: Isomeric transition
^ Bold for stable isotopes, bold italics for nearly stable isotopes (half-life longer than the age of the universe)
^ Believed to undergo α decay to ¹⁸⁰W or β⁺β⁺ decay to ¹⁸⁴W with a half-life over 56×10¹² years
^ primordial radionuclide
^ ^a ^b Used in rhenium-osmium dating
^ Believed to undergo α decay to ¹⁸³W
^ Believed to undergo α decay to ¹⁸⁴W
^ Believed to undergo α decay to ¹⁸⁵W
^ Believed to undergo α decay to ¹⁸⁶W
^ Believed to undergo α decay to ¹⁸⁸W or β⁻β⁻ decay to ¹⁹²Pt with a half-life over 9.8×10¹² years

Notes

Evaluated isotopic composition is for most but not all commercial samples.
The precision of the isotope abundances and atomic mass is limited through variations. The given ranges should be applicable to any normal terrestrial material.
Geologically exceptional samples are known in which the isotopic composition lies outside the reported range. The uncertainty in the atomic mass may exceed the stated value for such specimens.
Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC, which use expanded uncertainties.

References

^ 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.
^ Peters, Stefan T.M.; Münker, Carsten; Becker, Harry; Schulz, Toni (April 2014). "Alpha-decay of ¹⁸⁴Os revealed by radiogenic ¹⁸⁰W 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.
^ "Standard Atomic Weights: Osmium". CIAAW. 1991.
^ 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.
^ Flegenheimer, Juan (2014). "The mystery of the disappearing isotope" (PDF). Revista Virtual de Química. 6 (4): 1139–1142.
^ "Universal Nuclide Chart". nucleonica. {{cite web}}: Unknown parameter |registration= ignored (|url-access= suggested) (help)

Isotope masses from:
- G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. Archived from the original (PDF) on 2008-09-23. {{cite journal}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)
Isotopic compositions and standard atomic masses from:
- J. R. de Laeter; J. K. Böhlke; P. De Bièvre; H. Hidaka; H. S. Peiser; K. J. R. Rosman; P. D. P. Taylor (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
- M. E. Wieser (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051. {{cite journal}}: Unknown parameter |laysummary= ignored (help)
Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
- G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. Archived from the original (PDF) on 2008-09-23. {{cite journal}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)
- National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. Retrieved September 2005. {{cite web}}: Check date values in: |accessdate= (help)
- N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide (ed.). CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0-8493-0485-9. {{cite book}}: Unknown parameter |nopp= ignored (|no-pp= suggested) (help)

[6] Bold for isotopes with half-lives longer than the age of the universe (nearly stable)

[8] Abbreviations:
EC: Electron capture
IT: Isomeric transition

[9] Bold for stable isotopes, bold italics for nearly stable isotopes (half-life longer than the age of the universe)

[10] Believed to undergo α decay to ¹⁸⁰W or β⁺β⁺ decay to ¹⁸⁴W with a half-life over 56×10¹² years

[11] rimordial radionuclide

[RD-12] Used in rhenium-osmium dating

[13] Believed to undergo α decay to ¹⁸³W

[14] Believed to undergo α decay to ¹⁸⁴W

[15] Believed to undergo α decay to ¹⁸⁵W

[16] Believed to undergo α decay to ¹⁸⁶W

[17] Believed to undergo α decay to ¹⁸⁸W or β⁻β⁻ decay to ¹⁹²Pt with a half-life over 9.8×10¹² years

[NUBASE2020-1] 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.

[184Os-2] Peters, Stefan T.M.; Münker, Carsten; Becker, Harry; Schulz, Toni (April 2014). "Alpha-decay of ¹⁸⁴Os revealed by radiogenic ¹⁸⁰W 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.

[CIAAW2021-4] 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" (PDF). Revista Virtual de Química. 6 (4): 1139–1142.

[7] "Universal Nuclide Chart". nucleonica. {{cite web}}: Unknown parameter |registration= ignored (|url-access= suggested) (help)

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