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Isotopes of Selenium

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

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

All atomic nuclei of the chemical element selenium are summarized under selenium isotopes; these all consist of an atomic nucleus with 34 protons and, in the uncharged state, 34 electrons. The difference between each selenium isotope is based on the number of neutrons in the nucleus.

 

Naturally Occurring Selenium Isotopes

Natural terrestrial selenium deposits are made up of six different isotopes which - with the exception of the quasi-stable selenium 82 - are considered to be stable.

Atomic Mass maQuantityHalf-lifeSpin
Selenium
Isotopic mixture		78,971 u100 %
Isotope 74Se73,9224759(1) u0,86(3) %stable0+
Isotope 76Se75,9192137(2) u9,23(7) %stable0+
Isotope 77Se76,9199142(5) u7,60(7) %stable1/2-
Isotope 78Se77,917309(2) u23,69(22) %stable0+
Isotope 80Se79,916522(8) u49,80(36) %stable0+
Isotope 82Se81,916700(9) u8,82(15) %9.39(17) × 1019 a0+

 

The average atomic mass can vary due to fluctuations in the isotopic composition of natural selenium.

 

Isotope Table: Selenium

The two following tables list the most important data and properties of the Selenium isotopes. Further information on the individual Selenium 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
Selenium-636334Se2962.98191(54) u
[62.9632589 u]
{-16.85073 MeV}
Selenium-646434Se3063.97134(54) u
[63.9526889 u]
{-26.69662 MeV}		0+
Selenium-656534Se3164.96455(32) u
[64.9458989 u]
{-33.02146 MeV}		(3/2-)
Selenium-666634Se3265.95528(21) u
[65.9366289 u]
{-41.65641 MeV}		0+
Selenium-676734Se3366.94999(7) u
[66.9313389 u]
{-46.58401 MeV}
Selenium-686834Se3467.9418252(5) u
[67.9231741 u]
{-54.18948 MeV}		0+
Selenium-696934Se3568.9394148(16) u
[68.9207637 u]
{-56.43475 MeV}		1/2-
Selenium-69m169m134Se3568.9394148(16) u
[68.9207637 u]
{-56.43475 MeV}		5/2-
Selenium-69m269m234Se3568.9394148(16) u
[68.9207637 u]
{-56.43475 MeV}		9/2+
Selenium-707034Se3669.9335155(17) u
[69.9148644 u]
{-61.92991 MeV}		0+70Br
Selenium-717134Se3770.932209(3) u
[70.9135579 u]
{-63.14691 MeV}		(5/2-)71Br
Selenium-71m171m134Se3770.932209(3) u
[70.9135579 u]
{-63.14691 MeV}		(1/2-)
Selenium-71m271m234Se3770.932209(3) u
[70.9135579 u]
{-63.14691 MeV}		(9/2+)
Selenium-727234Se3871.9271405(21) u
[71.9084894 u]
{-67.86819 MeV}		0+72Br
73Kr
Selenium-737334Se3972.926755(8) u
[72.9081039 u]
{-68.22728 MeV}		9/2+73Br
Selenium-73m73m34Se3972.926755(8) u
[72.9081039 u]
{-68.22728 MeV}		3/2-
Selenium-747434Se4073.9224759(1) u
[73.9038248 u]
{-72.21323 MeV}		0+74Br
74As
Selenium-757534Se4174.92252287(8) u
[74.9038718 u]
{-72.16948 MeV}		5/2+75Br
Selenium-767634Se4275.9192137(2) u
[75.9005626 u]
{-75.25195 MeV}		0+76Br
76As
Selenium-777734Se4376.9199142(5) u
[76.9012631 u]
{-74.59944 MeV}		1/2-77Br
77As
Selenium-77m77m34Se4376.9199142(5) u
[76.9012631 u]
{-74.59944 MeV}		7/2+
Selenium-787834Se4477.917309(2) u
[77.8986579 u]
{-77.02617 MeV}		0+78Br
78As
Selenium-797934Se4578.91849925(24) u
[78.8998482 u]
{-75.91746 MeV}		7/2+79As
Selenium-79m79m34Se4578.91849925(24) u
[78.8998482 u]
{-75.91746 MeV}		1/2-
Selenium-808034Se4679.916522(8) u
[79.8978709 u]
{-77.75926 MeV}		0+80As
80Br
Selenium-818134Se4780.9179930(11) u
[80.8993419 u]
{-76.38903 MeV}		1/2-81As
Selenium-81m81m34Se4780.9179930(11) u
[80.8993419 u]
{-76.38903 MeV}		7/2+
Selenium-828234Se4881.916700(9) u
[81.8980489 u]
{-77.59345 MeV}		0+82As
Selenium-838334Se4982.919119(3) u
[82.9004679 u]
{-75.34017 MeV}		9/2+83As
Selenium-83m83m34Se4982.919119(3) u
[82.9004679 u]
{-75.34017 MeV}		1/2-
Selenium-848434Se5083.9184668(21) u
[83.8998157 u]
{-75.94769 MeV}		0+84As
85As
Selenium-858534Se5184.9222608(28) u
[84.9036097 u]
{-72.4136 MeV}		(5/2)+85As
Selenium-868634Se5285.9243117(27) u
[85.9056606 u]
{-70.5032 MeV}		0+86As
87As
Selenium-878734Se5386.9286886(24) u
[86.9100375 u]
{-66.42614 MeV}		(3/2+)
Selenium-888834Se5487.931417(4) u
[87.9127659 u]
{-63.88465 MeV}		0+
Selenium-898934Se5588.936669(4) u
[88.9180179 u]
{-58.99245 MeV}		(5/2+)
Selenium-909034Se5689.94010(35) u
[89.9214489 u]
{-55.79649 MeV}		0+
Selenium-919134Se5790.94570(46) u
[90.9270489 u]
{-50.58012 MeV}
Selenium-929234Se5891.94984(43) u
[91.9311889 u]
{-46.72374 MeV}		0+
Selenium-939334Se5992.95629(43) u
[92.9376389 u]
{-40.7156 MeV}		(1/2+)
Selenium-949434Se6093.96049(54) u
[93.9418389 u]
{-36.80333 MeV}		0+
Selenium-959534Se6194.96730(54) u
[94.9486489 u]
{-30.45985 MeV}

 

Radioactive Decay Properties

IsotopeRadioactive DecayExtern
Half-lifeDecay ModeProbabilityEnergy
789101112
Se-6313.2(39) msEC/β+ → 63As
EC, p → 62Ge
2p → 61Ge		11 %
89 %
< 0.5 %
Se-64180 nsEC/β+ → 64As100 %12.83(54) MeV
Se-6533(4) msEC/β+ → 65As
EC, p → 64Ge
13.92(31) MeV
AL
Se-6642(12) msEC → 66As100 %10.37(20) MeVAL
Se-67136(12) msEC/β+ → 67As
β+, p → 66Ge		99.5 %
0.5(1) %		10.01(7) MeV
AL
Se-6835.5(7) sEC/β+ → 68As100 %4.7051(19) MeVAL
Se-6927.4(2) sEC/β+ → 69As
EC, p → 68Ge		99.958 %
0.052(8) %		6.68(3) MeV
AL
Se-69m12.0(2) μs
Se-69m2960(23) ns
Se-7041.1(3) minEC/β+ → 70As100 %2.41(5) MeVAL
Se-714.74(5) minEC/β+ → 71As100 %4.747(5) MeVAL
Se-71m15.6(7) μs
Se-71m219.0(5) μs
Se-728.40(8) dEC → 72As100 %0.362(5) MeVAL
Se-737.15(9) hEC/β+ → 73As100 %2.725(8) MeVAL
Se-73m39.8(17) minEC/β+ → 73As
Iso → 73As		27.4(3) %
72.6(3) %
AL
Se-74stableAL
Se-75119.78(5) dEC → 75As100 %0.8647(9) MeVAL
Se-76stableAL
Se-77stableAL
Se-77m17.36(5) sIso → 77Se100 %AL
Se-78stableAL
Se-793.27(28) × 105 aβ- → 79Br100 %0.1506(10) MeVAL
Se-79m3.92(1) minβ- → 79Br
Iso → 79Se		0.056(11) %
99.944(11) %
AL
Se-80stable2 β-? AL
Se-8118.45(12) minβ- → 81Br100 %1.5880(14) MeVAL
Se-81m57.28(2) minβ- → 81Br
Iso → 81Se		0.051(14) %
99.949(14) %
AL
Se-829.39(17) × 1019 a2β- → 82Kr100 %AL
Se-8322.3(3) minβ- → 83Br100 %3.673(5) MeVAL
Se-83m70.1(4) sβ- → 83Br100 %AL
Se-843.26(10) minβ- → 84Br100 %1.835(26) MeVAL
Se-8532.9(3) sβ- → 85Br100 %6.162(4) MeVAL
Se-8614.3(3) sβ- → 86Br100 %5.129(4) MeVAL
Se-875.50(14) sβ- → 87Br
β-, n → 86Br		99.64 %
0.36(8) %		7.466(4) MeV
1.135(4) MeV		AL
Se-881.53(6) sβ- → 88Br
β-, n → 87Br		99.33 %
0.67(30) %		6.832(5) MeV
1.936(5) MeV		AL
Se-890.43(5) sβ- → 89Br
β-, n → 88Br		92.2(25) %
7.8(25) %		9.282(5) MeV
3.652(5) MeV		AL
Se-90195 msβ- → 90Br
β-, n → 89Br
?		8.20(33) MeV
4.40(33) MeV		AL
Se-910.27(5) sβ- → 91Br
β-, n → 90Br		79(10) %
21(10) %		10.53(43) MeV
5.35(43) MeV		AL
Se-92β- → 92Br100 %9.51(40) MeVAL
Se-93β- → 93Br100 %12.17(59) MeVAL
Se-94150 nsβ- → 94Br100 %10.60(58) MeVAL
Se-95392 nsβ- → 93Br
β-, n → 92Br
β-, 2n → 91Br		?
?
?		13.31(58) 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 Selenium 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 Selenium 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 Selenium 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)
77Se
7,60(7) %
1/2-		+0,53356(5)5,1214
{0,760}		8,15680,00703
0,1916

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 Selenium radionuclides:

NuclideLimit ValueHASS limitSCDaughter NuclidesHalf-life
Se-70106 Bq10 Bq/g41.1 min
Se-73106 Bq10 Bq/g7.2 h
Se-73m106 Bq100 Bq/g39.8 min
Se-75106 Bq1 Bq/g0,2 TBq10 Bq cm-2119.6 d
Se-79107 Bq0,1 Bq/g20 TBq380000 a
Se-81106 Bq1000 Bq/g18.4 min
Se-81m+107 Bq1000 Bq/g57.3 min
Se-83105 Bq10 Bq/g22.3 min

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

 

Literature Sources and References

Properties of the Selenium 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.

Selenium: NMR properties - 77Se-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] - B. Srinivasan, E. C. Alexander, R. D. Beaty, D. E. Sinclair, O. K. Manuel:
Double Beta Decay of Selenium-82.
In: Economic Geology, (1973), DOI 10.2113/​gsecongeo.68.2.252.

[10] - B. Srinivasan, E. C. Alexander, R. D. Beaty, D. E. Sinclair, O. K. Manuel:
Preparation of radiochemically pure 79Se and highly precise determination of its half-life.
In: Applied Radiation and Isotopes, (2010), DOI 10.1016/j.apradiso.2010.05.006.

[11] - Nagmeddin Elwaer und Holger Hintelmann:
Precise selenium isotope ratios measurement using a multimode sample introduction system (MSIS) coupled with multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS).
In: Journal of Analytical Atomic Spectrometry, (2008), DOI 10.1039/B808645C.

[12] - Kathrin Schilling:
Stable isotope fractionation of selenium by biomethylation in soil.
In: Dissertation, Universität Mainz, (2010).

[13] - J.L. Gross, J. Claes, J. Kathawa, M. Thoennessen:
Discovery of zinc, selenium, bromine, and neodymium isotopes.
In: Atomic Data and Nuclear Data Tables, (2012), DOI 10.1016/j.adt.2011.12.001.

 

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