Isotopes of selenium

Selenium (Se) has six naturally occurring isotopes, five of which 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,^[1]^[2] and ⁸²Se which has a very long half-life (~10²⁰ yr, decaying via double beta decay to ⁸²Kr) and for practical purposes can be considered to be stable. 23 other unstable isotopes 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. All other isotopes have half-lives less than 8 hours, most less than 38 seconds, which of these, ⁷³Se is the most stable, with a half-life of 7.15 hours.

Standard atomic mass: 78.96(3) u

1 Table
- 1.1 Notes
2 See also
3 References

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life^{[n 1]}	decay mode(s)^[3]^{[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)^[3]^{[n 2]}	daughter isotope(s)^{[n 3]}	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
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 4]}			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 5]}	34	45	78.9184991(18)	3.27(8)×10⁵ a	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 6]}			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 7]}	34	48	81.9166994(22)	97(5)×10¹⁸ a	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%)	⁸⁸Br	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+

^ 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
^ Believed to decay by β⁺β⁺ to ⁷⁴Ge
^ Long-lived fission product
^ Believed to decay by β^-β^- to ⁸⁰Kr
^ Primordial radionuclide

Notes

The precision of the isotope abundances and atomic mass is limited through variations. The given ranges should be applicable to any normal terrestrial material.
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

^ The half-life of ⁷⁹Se
^ 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.
^ http://www.nucleonica.net/unc.aspx

Isotope masses from:
- G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (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. http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf.
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 and 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. http://www.iupac.org/publications/pac/75/6/0683/pdf/.
- 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. http://iupac.org/publications/pac/78/11/2051/pdf/. Lay summary.
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 and O. Bersillon (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. http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf.
- National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. http://www.nndc.bnl.gov/nudat2/. Retrieved September 2005.
- N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide. CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0849304859.

Isotopes of arsenic	Isotopes of selenium	Isotopes of bromine
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Isotopes of selenium

Contents

Table

Notes

See also

References