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Isotopes of Osmium

List, data and properties of all known isotopes of Osmium.

Content
Atomic properties
Decay properties
NMR active nuclides
Radiation protection
References
Osmium isotopes

All atomic nuclei of the chemical element osmium are summarized under osmium isotopes; these all consist of an atomic nucleus with 76 protons and, in the uncharged state, 76 electrons. The difference between each osmium isotope is based on the number of neutrons in the nucleus.

 

Naturally Occurring Osmium Isotopes

Natural osmium deposits are composed of 7 isotopes, two of which are unstable radioisotopes:

Atomic Mass maQuantityHalf-lifeSpin
Osmium
Isotopic mixture		190,23 u100 %
Isotope 184Os183,952489(9) u0,02(1) %5.6 × 1013 a0+
Isotope 186Os185,95384(1) u1,59(3) %2.0(11) × 1015 a0+
Isotope 187Os186,95575(1) u1,96(2) %stable1/2-
Isotope 188Os187,95584(1) u13,24(8) %stable0+
Isotope 189Os188,95814(2) u16,15(5) %stable3/2-
Isotope 190Os189,95844(2) u26,26(2) %stable0+
Isotope 192Os191,96148(2) u40,78(19) %stable0+

 

All other osmium nuclides known and characterized so far are unstable.

 

Isotope Table: Osmium

The two following tables list the most important data and properties of the Osmium isotopes. Further information on the individual Osmium isotopes is listed on separate pages and can be accessed via the link in column 1.

 

Atomic Properties

Isotope
Nuclide		ENAtomic Mass
[Nuclear Mass]
{Mass Excess}		Spin I
(h/2π)		Parent
123456
Osmium-16116176Os85160.98929(43) u
[160.9476022 u]
{-9.9763 MeV}		(7/2-)
Osmium-16216276Os86161.98450(32) u
[161.9428122 u]
{-14.43816 MeV}		0+166Pt
Osmium-16316376Os87162.98262(32) u
[162.9409322 u]
{-16.18937 MeV}		(7/2-)167Pt
Osmium-16416476Os88163.97808(16) u
[163.9363922 u]
{-20.41835 MeV}		0+168Pt
165Ir
Osmium-16516576Os89164.97660(21) u
[164.9349122 u]
{-21.79696 MeV}		(7/2-)169Pt
166Ir
Osmium-16616676Os90165.972698(19) u
[165.9310102 u]
{-25.43165 MeV}		0+170Pt
Osmium-16716776Os91166.97155(8) u
[166.9298622 u]
{-26.501 MeV}		(7/2-)171Pt
Osmium-16816876Os92167.967799(11) u
[167.9261112 u]
{-29.99504 MeV}		0+172Pt
Osmium-16916976Os93168.967018(27) u
[168.9253302 u]
{-30.72254 MeV}		(5/2-)173Pt
Osmium-17017076Os94169.963579(10) u
[169.9218912 u]
{-33.92594 MeV}		0+174Pt
170Ir
Osmium-17117176Os95170.963175(19) u
[170.9214872 u]
{-34.30227 MeV}		(5/2-)175Pt
Osmium-17217276Os96171.960017(14) u
[171.9183292 u]
{-37.24392 MeV}		0+176Pt
172Ir
Osmium-17317376Os97172.959808(16) u
[172.9181202 u]
{-37.43861 MeV}		5/2-177Pt
173Ir
Osmium-17417476Os98173.957063(11) u
[173.9153752 u]
{-39.99556 MeV}		0+178Pt
174Ir
Osmium-17517576Os99174.956945(13) u
[174.9152572 u]
{-40.10547 MeV}		(5/2-)179Pt
175Ir
Osmium-17617676Os10017595481(3) u
[175.9131222 u]
{-42.09421 MeV}		0+180Pt
176Ir
Osmium-17717776Os101176.954958(16) u
[176.9132702 u]
{-41.95635 MeV}		1/2-181Pt
177Ir
Osmium-17817876Os102177.953253(15) u
[177.9115652 u]
{-43.54455 MeV}		0+182Pt
178Ir
Osmium-17917976Os103178.953817(18) u
[178.9121292 u]
{-43.01919 MeV}		1/2-183Pt
179Ir
Osmium-18018076Os104179.952380(18) u
[179.9106922 u]
{-44.35774 MeV}		0+184Pt
180Ir
Osmium-18118176Os105180.953247(27) u
[180.9115592 u]
{-43.55014 MeV}		1/2-185Pt
181Ir
Osmium-181m181m76Os105180.953247(27) u
[180.9115592 u]
{-43.55014 MeV}		7/2-
Osmium-18218276Os106181.952110(23) u
[181.9104222 u]
{-44.60925 MeV}		0+186Pt
182Ir
Osmium-182m182m76Os106181.952110(23) u
[181.9104222 u]
{-44.60925 MeV}		(8)-
Osmium-18318376Os107182.95312(5) u
[182.9114322 u]
{-43.66844 MeV}		9/2+183Ir
Osmium-183m183m76Os107182.95312(5) u
[182.9114322 u]
{-43.66844 MeV}		1/2-
Osmium-18418476Os108183.952489(9) u
[183.9108012 u]
{-44.25621 MeV}		0+188Pt
184Ir
Osmium-18518576Os109184.9540460(9) u
[184.9123582 u]
{-42.80588 MeV}		1/2-185Ir
Osmium-185m1185m176Os109184.9540460(9) u
[184.9123582 u]
{-42.80588 MeV}		7/2-
Osmium-185m2185m276Os109184.9540460(9) u
[184.9123582 u]
{-42.80588 MeV}		11/2+
Osmium-18618676Os110185.95384(1) u
[185.9121522 u]
{-42.99776 MeV}		0+186Ir
186Re
190Pt
Osmium-18718776Os111186.95575(1) u
[186.9140622 u]
{-41.21861 MeV}		1/2-187Ir
187Re
Osmium-18818876Os112187.95584(1) u
[187.9141522 u]
{-41.13478 MeV}		0+188Ir
188Re
Osmium-18918976Os113188.95814(2) u
[188.9164522 u]
{-38.99234 MeV}		3/2-189Ir
189Re
Osmium-189m189m76Os113188.95814(2) u
[188.9164522 u]
{-38.99234 MeV}		9/2-
Osmium-19019076Os114189.95844(2) u
[189.9167522 u]
{-38.71289 MeV}		0+190Ir
190Re
Osmium-190m190m76Os114189.95844(2) u
[189.9167522 u]
{-38.71289 MeV}		(10)-
Osmium-19119176Os115190.9609282(7) u
[190.9192404 u]
{-36.39515 MeV}		9/2-
Osmium-191m191m76Os115190.9609282(7) u
[190.9192404 u]
{-36.39515 MeV}		3/2-
Osmium-19219276Os116191.96148(2) u
[191.9197922 u]
{-35.88115 MeV}		0+192Ir
192Re
Osmium-192m192m76Os116191.96148(2) u
[191.9197922 u]
{-35.88115 MeV}		(10-)
Osmium-192m2192m276Os116191.96148(2) u
[191.9197922 u]
{-35.88115 MeV}		(16+)
Osmium-19319376Os117192.9641498(25) u
[192.922462 u]
{-33.39425 MeV}		3/2-
Osmium-19419476Os118193.9651795(26) u
[193.9234917 u]
{-32.43509 MeV}		0+
Osmium-19519576Os119194.96832(6) u
[194.9266322 u]
{-29.50973 MeV}		(3/2-)
Osmium-195m195m76Os119194.96832(6) u
[194.9266322 u]
{-29.50973 MeV}
Osmium-19619676Os120195.96964(4) u
[195.9279522 u]
{-28.28016 MeV}		0+
Osmium-19719776Os121196.97283(21) u
[196.9311422 u]
{-25.30869 MeV}
Osmium-19819876Os122197.97441(21) u
[197.9327222 u]
{-23.83693 MeV}		0+
Osmium-19919976Os123198.97801(21) u
[198.9363222 u]
{-20.48355 MeV}
Osmium-20020076Os124199.97984(32) u
[199.9381522 u]
{-18.77892 MeV}		0+
Osmium-20120176Os125200.98364(32) u
[200.9419522 u]
{-15.23924 MeV}
Osmium-20220276Os126201.98595(43) u
[201.9442622 u]
{-13.08749 MeV}		0+
Osmium-20320376Os127202.99180(43) u
[202.9501122 u]
{-7.63825 MeV}

 

Radioactive Decay Properties

IsotopeRadioactive DecayExtern
Half-lifeDecay ModeProbabilityEnergy
789101112
Os-1610.64(4) msα → 157Wca. 100 %7.066(12) MeVAL
Os-1622.1(1) msα → 158Wca. 99 %6.767(3) MeVAL
Os-1635.5(6) msα → 159W
EC/β+ → 163Re		ca. 100 %
?		6.677(8) MeV
9.81(30) MeV		AL
Os-16421(1) msα → 160W
EC/β+ → 164Re		96 %
4 %		6.479(5) MeV
7.05(16) MeV		AL
Os-16571(3) msα → 161W
EC/β+ → 165Re		90(2) %
10(2) %		6.335(6) MeV
8.86(20) MeV		AL
Os-166213(5) msα → 162W
EC/β+ → 166Re		72(13) %
28(13) %		6.143(3) MeV
6.46(7) MeV		AL
Os-1670.81(6) sα → 163W
EC/β+ → 167Re		57(8) %
43(8) %		5.98(5) MeV
8.33(8) MeV		AL
Os-1682.1(1) sα → 164W
EC/β+ → 168Re		43(4) %
57(4) %		5.8156(27) MeV
5.80(3) MeV		AL
Os-1693.43(14) sα → 165W
EC/β+ → 169Re		13.7(8) %
86.3(8) %		5.713(3) MeV
7.687(28) MeV		AL
Os-1707.37(18) sα → 166W
EC/β+ → 170Re		9.5(10) %
90.5(10) %		5.5369(27) MeV
4.987(25) MeV		AL
Os-1718.3(2) sα → 167W
EC/β+ → 171Re		1.80(21) %
98.20(21) %		5.371(4) MeV
6.95(3) MeV		AL
Os-17219.2(9) sα → 168W
EC/β+ → 172Re		0.2 %
99.8 %		5.224(7) MeV
4.29(4) MeV		AL
Os-17322.4(9) sα → 169W
EC/β+ → 173Re		0.4(2) %
99.6(2) %		5.055(6) MeV
6.12(3) MeV		AL
Os-17444(4) sα → 170W
EC → 174Re		0.020 %
99.98 %		4.87(10) MeV
3.68(3) %		AL
Os-1751.4(1) minEC/β+ → 175Re100 %5.18(3) MeVAL
Os-1763.6(5) minEC/β+ → 176Re100 %2.96(4) MeVAL
Os-1773.0(2) minEC/β+ → 177Re100 %4.31(3) MeVAL
Os-1785.0(4) minEC/β+ → 178Re
α → 174W		ca. 100 %
≥ 0 %		2.11(3) MeV
4.26(3) MeV		AL
Os-1796.5(3) minEC/β+ → 179Re100 %3.56(3) MeVAL
Os-18021.5(4) minEC/β+ → 180Re100 %1.48(27) MeVAL
Os-181105(3) minEC/β+ → 181Re100 %2.967(28) MeVAL
Os-181m2.7(1) minEC/β+ → 181Re
Iso → 181Os		ca. 97 %
≤ 3 %
Os-18221.84(20) hEC → 182Re100 %0.84(10) MeVAL
Os-182m0.78(7) msIso → 182Os100 %
Os-18313.0(5) hEC/β+ → 183Re100 %2.15(5) MeVAL
Os-183m9.9(3) hEC/β+ → 183Re
Iso → 183Os		85(2) %
15(2) %
Os-1845.6 × 1013 aα → 180W
2 β+ 184W		?
?		2.9587(16) MeV
AL
Os-18593.6(5) dEC → 185Re100 %1.0131(12) MeVAL
Os-185m13.0(4) μs
Os-185m20.78(5) μs
Os-1862.0(11) × 1015 aα → 182W100 %2.8212(9) MeVAL
Os-187stableAL
Os-188stableAL
Os-189stableAL
Os-189m5.81(10) hIso → 189Os100 %
Os-190stableAL
Os-190m9.9(1) minIso → 190Os100 %
Os-19115.4(1) dβ- → 191Ir100 %0.3136(11) MeVAL
Os-191m13.10(5) hIso → 191Os100 %
Os-192stableAL
Os-192m5.9(1) sβ- → 192Ir
Iso → 192Os		< 13 %
> 87 %
Os-192m20.19(10) μsIso → 192Os100 %
Os-19329.830(18) hβ- → 193Ir100 %1.1419(24) MeVAL
Os-1946.0(2) aβ- → 194Ir100 %0.0966(20) MeVAL
Os-1956.5(11) minβ- → 195Ir?2.18(6) MeVAL
Os-195m9 minIso → 195Os
β- → 195Ir		> 0 %
?
Os-19634.9(2) minβ- → 196Ir100 %1.16(6) MeVAL
Os-1972.8(6) minβ- → 197Ir100 %2.95(20) MeVAL
Os-198β- → 198Ir100 %1.98(28) MeVAL
Os-1995 sβ- → 199Ir100 %3.91(20) MeVAL
Os-2006 sβ- → 200Ir100 %2.83(36) MeVAL
Os-201160 nsβ- → 201Ir?4.66(36) MeV
Os-202160 nsβ- → 202Ir?3.69(50) MeV
Os-203β- → 203Ir
β-, n → 202Ir		?
?		7.05(57) MeV
1.06(50) MeV

 

Notes (related to the columns):

1 - name of the nuclide, isotope.
2 - E: isotope symbol with mass number (superscript; number of nucleons) and Atomic number (subscript; number of protons).
3 - N: number of neutrons.
4 - relative atomic mass of the Osmium isotope (isotopic mass including electrons) and the mass of the atomic nucleus in square brackets (nuclear mass, nuclide mass without electrons), each related to 12C = 12.00000 [2]. In addition, the mass excess is given in MeV.
5 - nuclear spin I, unit: h/2π.
6 - source nuclides: Possible, assumed or actual source nuclides (mother nuclides, parent nuclides). If applicable, the corresponding decay modes can be found in the data for the respective starting nuclide.

7 - isotope notation in short form.
8 - decay: half-live of the Osmium isotope (a = years; ; d = days; h = hours; min = minutes; s = seconds).
9 - decay mode: type of decay into the respective daughter nuclides with n = neutron emission; p = proton emission; α = alpha decay; β- = beta minus decay with electron emission; EC = electron capture; β+ = positron emission; ε = β+ and/or EC; Iso = isomeric transition; CD = cluster decay; SF = spontaneous decay.
10 - decay probability in percent (%).
11 - decay energy; Particle energy related to decay type.
12 - other information and notes: AL = Adopted Levels (link to external data [1]).

Miscellaneous:

()- Numbers in brackets: uncertainty to represent the spread of the reported value.
~ - Theoretical values or systematic trends.
  - unlisted-: Nuclides that have already been mentioned in the literature but for some reason can no longer be found in the current nuclide tables because their discovery e.g. has not confirmed.

 

NMR active Osmium nuclides

Nuclide
quantity 1)
spin		Nuclear
magnetic
moment
μ/μN		Gyromagnetic ratio
{Quadrupole moment}		Resonant
frequency
v0 bei 1 T		Relative
sensitivity
H0 = const.
v0 = const. 3)
187Os
1,96(2) %
1/2-		+ 0,06465189(6)
{}		0,98560,00001
0,0231
189Os
16,15(5) %
3/2-		+ 0,659933(4)
{+ 0,856(28)}		3,35360,00244
0,3938

1) Quantity Percentage of natural occurrence.

2) Gyromagnetic ratio: 107 rad T-1 s-1
    Quadrupole moment: Q [barn] = [100 fm2]

3) Related to 1H = 1,000.

 

Radiation Protection

According to the Radiation Protection Ordinance (StrlSchV 2018, Germany), the following values (columns 1 to 7) apply to the handling of Osmium radionuclides:

NuclideLimit ValueHASS limitSCDaughter NuclidesHalf-life
Os-180107 Bq100 Bq/g21.5 min
Os-181106 Bq10 Bq/g1.8 h
Os-182106 Bq100 Bq/g22.1 h
Os-185106 Bq1 Bq/g0,1 TBq1 Bq cm-293.8 d
Os-189m107 Bq10000 Bq/g5.8 h
Os-191+107 Bq100 Bq/g10 Bq cm-215.3 d
Os-191m107 Bq1000 Bq/g100 Bq cm-213.1 h
Os-193106 Bq100 Bq/g1 TBq10 Bq cm-230.1 h
Os-194+105 Bq1 Bq/g0,7 TBqIr-1946.0 a

(HASS = High-Activity Sealed Radioactive Sources; SC = surface contamination)

 

Literature Sources and References

Properties of the Osmium nucleides

[1] - NuDat: National Nuclear Data Center, Brookhaven National Laboratory, based on ENSDF and the Nuclear Wallet Cards.

[2] - G. Audi et. al.: The NUBASE evaluation of nuclear and decay properties. Nuclear Physics, (2003), DOI 10.1016/j.nuclphysa.2003.11.001.

[3] - Live Chart of Nuclides. Nuclear structure and decay data.

Osmium: NMR properties - 187Os-NMR, 189Os-NMR

[4] - N. J. Stone: Table of nuclear magnetic dipole and electric quadrupole moments. Atomic Data and Nuclear Data Tables, (2005), DOI 10.1016/j.adt.2005.04.001.

[5] - Pekka Pyykkö: Year-2008 nuclear quadrupole moments. Molecular Physics, (2008), DOI 10.1080/00268970802018367.

[6] - Pekka Pyykkö: Year-2017 nuclear quadrupole moments. Molecular Physics, (2018), DOI 10.1080/00268976.2018.1426131.

[7] - N. J. Stone: Table of recommended nuclear magnetic dipole moments. IAEA, (2019).

More sources:

[8] - Isotopic abundances, atomic weights and isotopic masses: see respective keyword.

[9] - J. W. Arblaster:
The Discoveries of the Osmium Isotopes.
In: Platinum Metals Review, (2009), DOI 10.1595/147106704X4826.

[10] - R. Robinson, M. Thoennessen:
Discovery of tantalum, rhenium, osmium, and iridium isotopes.
In: Atomic Data and Nuclear Data Tables, (2012), DOI 10.1016/j.adt.2011.09.003.

 

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