Isotopes of selenium

Isotopes of selenium (₃₄Se)
γ	–
γ	–
Standard atomic weight Ar°(Se)
	78.971±0.008; 78.971±0.008 (abridged);
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Selenium (₃₄Se) has six natural isotopes that occur in significant quantities, along with the trace isotope ⁷⁹Se, which occurs in minute quantities in uranium ores. Five of these isotopes are stable: ⁷⁴Se, ⁷⁶Se, ⁷⁷Se, ⁷⁸Se, and ⁸⁰Se. The last three also occur as fission products, along with ⁷⁹Se, which has a half-life of 327,000 years,^[4]^[5] and ⁸²Se, which has a very long half-life (~10²⁰ years, decaying via double beta decay to ⁸²Kr) and for practical purposes can be considered to be stable. There are 23 other unstable isotopes that have been characterized, the longest-lived being ⁷⁹Se with a half-life 327,000 years, ⁷⁵Se with a half-life of 120 days, and ⁷²Se with a half-life of 8.40 days. Of the other isotopes, ⁷³Se has the longest half-life, 7.15 hours; most others have half-lives not exceeding 38 seconds.

List of isotopes

Nuclide ^{[n 1]}	Z	N	Isotopic mass (Da) ^{[n 2]}^{[n 3]}	Half-life ^{[n 4]}^{[n 5]}	Decay mode ^{[n 6]}	Daughter isotope ^{[n 7]}	Spin and parity ^{[n 8]}^{[n 5]}	Natural abundance (mole fraction)
Nuclide ^{[n 1]}	Excitation energy			Half-life ^{[n 4]}^{[n 5]}	Decay mode ^{[n 6]}	Daughter isotope ^{[n 7]}	Spin and parity ^{[n 8]}^{[n 5]}	Normal proportion	Range of variation
⁶⁵Se	34	31	64.96466(64)#	<50 ms	β⁺ (>99.9%)	⁶⁵As	3/2−#
⁶⁵Se	34	31	64.96466(64)#	<50 ms	β⁺, p (<.1%)	⁶⁴Ge	3/2−#
⁶⁶Se	34	32	65.95521(32)#	33(12) ms	β⁺	⁶⁶As	0+
⁶⁷Se	34	33	66.95009(21)#	133(11) ms	β⁺ (99.5%)	⁶⁷As	5/2−#
⁶⁷Se	34	33	66.95009(21)#	133(11) ms	β⁺, p (.5%)	⁶⁶Ge	5/2−#
⁶⁸Se	34	34	67.94180(4)	35.5(7) s	β⁺	⁶⁸As	0+
⁶⁹Se	34	35	68.93956(4)	27.4(2) s	β⁺ (99.955%)	⁶⁹As	(1/2−)
⁶⁹Se	34	35	68.93956(4)	27.4(2) s	β⁺, p (.045%)	⁶⁸Ge	(1/2−)
^69m1Se	39.4(1) keV			2.0(2) μs			5/2−
^69m2Se	573.9(10) keV			955(16) ns			9/2+
⁷⁰Se	34	36	69.93339(7)	41.1(3) min	β⁺	⁷⁰As	0+
⁷¹Se	34	37	70.93224(3)	4.74(5) min	β⁺	⁷¹As	5/2−
^71m1Se	48.79(5) keV			5.6(7) μs			1/2− to 9/2−
^71m2Se	260.48(10) keV			19.0(5) μs			(9/2)+
⁷²Se	34	38	71.927112(13)	8.40(8) d	EC	⁷²As	0+
⁷³Se	34	39	72.926765(11)	7.15(8) h	β⁺	⁷³As	9/2+
^73mSe	25.71(4) keV			39.8(13) min	IT	⁷³Se	3/2−
^73mSe	25.71(4) keV			39.8(13) min	β⁺	⁷³As	3/2−
⁷⁴Se	34	40	73.9224764(18)	Observationally Stable ^{[n 9]}			0+	0.0089(4)
⁷⁵Se	34	41	74.9225234(18)	119.779(4) d	EC	⁷⁵As	5/2+
⁷⁶Se	34	42	75.9192136(18)	Stable			0+	0.0937(29)
⁷⁷Se	34	43	76.9199140(18)	Stable			1/2−	0.0763(16)
^77mSe	161.9223(7) keV			17.36(5) s	IT	⁷⁷Se	7/2+
⁷⁸Se	34	44	77.9173091(18)	Stable			0+	0.2377(28)
⁷⁹Se^{[n 10]}	34	45	78.9184991(18)	3.27(8)×10⁵ y	β⁻	⁷⁹Br	7/2+
^79mSe	95.77(3) keV			3.92(1) min	IT (99.944%)	⁷⁹Se	1/2−
^79mSe	95.77(3) keV			3.92(1) min	β⁻ (.056%)	⁷⁹Br	1/2−
⁸⁰Se	34	46	79.9165213(21)	Observationally Stable^{[n 11]}			0+	0.4961(41)
⁸¹Se	34	47	80.9179925(22)	18.45(12) min	β⁻	⁸¹Br	1/2−
^81mSe	102.99(6) keV			57.28(2) min	IT (99.948%)	⁸¹Se	7/2+
^81mSe	102.99(6) keV			57.28(2) min	β⁻ (.052%)	⁸¹Br	7/2+
⁸²Se^{[n 12]}	34	48	81.9166994(22)	0.97(5)×10²⁰ y	β⁻β⁻	⁸²Kr	0+	0.0873(22)
⁸³Se	34	49	82.919118(4)	22.3(3) min	β⁻	⁸³Br	9/2+
^83mSe	228.50(20) keV			70.1(4) s	β⁻	⁸³Br	1/2−
⁸⁴Se	34	50	83.918462(16)	3.1(1) min	β⁻	⁸⁴Br	0+
⁸⁵Se	34	51	84.92225(3)	31.7(9) s	β⁻	⁸⁵Br	(5/2+)#
⁸⁶Se	34	52	85.924272(17)	15.3(9) s	β⁻	⁸⁶Br	0+
⁸⁷Se	34	53	86.92852(4)	5.50(12) s	β⁻ (99.64%)	⁸⁷Br	(5/2+)#
⁸⁷Se	34	53	86.92852(4)	5.50(12) s	β⁻, n (.36%)	⁸⁶Br	(5/2+)#
⁸⁸Se	34	54	87.93142(5)	1.53(6) s	β⁻ (99.01%)	⁸⁸Br	0+
⁸⁸Se	34	54	87.93142(5)	1.53(6) s	β⁻, n (.99%)	⁸⁷Br	0+
⁸⁹Se	34	55	88.93645(32)#	0.41(4) s	β⁻ (92.2%)	⁸⁹Br	(5/2+)#
⁸⁹Se	34	55	88.93645(32)#	0.41(4) s	β⁻, n (7.8%)	⁸⁸Br	(5/2+)#
⁹⁰Se	34	56	89.93996(43)#	300# ms [>300 ns]	β⁻, n	⁸⁹Br	0+
⁹⁰Se	34	56	89.93996(43)#	300# ms [>300 ns]	β⁻	⁹⁰Br	0+
⁹¹Se	34	57	90.94596(54)#	270(50) ms	β⁻ (79%)	⁹¹Br	1/2+#
⁹¹Se	34	57	90.94596(54)#	270(50) ms	β⁻, n	⁹⁰Br	1/2+#
⁹²Se	34	58	91.94992(64)#	100# ms [>300 ns]	β⁻	⁹²Br	0+
⁹³Se	34	59	92.95629(86)#	50# ms [>300 ns]			1/2+#
⁹⁴Se	34	60	93.96049(86)#	20# ms [>300 ns]			0+
This table header & footer: view

^ ^mSe – Excited nuclear isomer.
^ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
^ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
^ Bold half-life – nearly stable, half-life longer than age of universe.
^ ^a ^b # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
^ Modes of decay:

EC: Electron capture

IT: Isomeric transition

n: Neutron emission

p: Proton emission
^ Bold symbol as daughter – Daughter product is stable.
^ ( ) spin value – Indicates spin with weak assignment arguments.
^ Believed to decay by β⁺β⁺ to ⁷⁴Ge
^ Long-lived fission product
^ Believed to decay by β⁻β⁻ to ⁸⁰Kr
^ Primordial radionuclide

Selenium-75

Radiopharmaceutical.

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.
^ "Standard Atomic Weights: Selenium". CIAAW. 2013.
^ 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.
^ The half-life of ⁷⁹Se Archived September 27, 2011, at the Wayback Machine
^ Jorg, Gerhard; Buhnemann, Rolf; Hollas, Simon; Kivel, Niko; Kossert, Karsten; Van Winckel, Stefaan; Gostomski, Christoph Lierse v. (2010). "Preparation of radiochemically pure 79Se and highly precise determination of its half-life". Applied Radiation and Isotopes. 68 (12): 2339–51. doi:10.1016/j.apradiso.2010.05.006. PMID 20627600.

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.

[6] Se – Excited nuclear isomer.

[7] ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.

[TMS-8] # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).

[9] Bold half-life – nearly stable, half-life longer than age of universe.

[TNN-10] # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).

[11] Modes of decay:

EC: Electron capture

IT: Isomeric transition

n: Neutron emission

p: Proton emission

[12] Bold symbol as daughter – Daughter product is stable.

[13] ( ) spin value – Indicates spin with weak assignment arguments.

[14] Believed to decay by β⁺β⁺ to ⁷⁴Ge

[15] Long-lived fission product

[16] Believed to decay by β⁻β⁻ to ⁸⁰Kr

[17] Primordial radionuclide

[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.

[2] "Standard Atomic Weights: Selenium". CIAAW. 2013.

[CIAAW2021-3] 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.

[life-4] The half-life of ⁷⁹Se Archived September 27, 2011, at the Wayback Machine

[5] Jorg, Gerhard; Buhnemann, Rolf; Hollas, Simon; Kivel, Niko; Kossert, Karsten; Van Winckel, Stefaan; Gostomski, Christoph Lierse v. (2010). "Preparation of radiochemically pure 79Se and highly precise determination of its half-life". Applied Radiation and Isotopes. 68 (12): 2339–51. doi:10.1016/j.apradiso.2010.05.006. PMID 20627600.

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