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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 halflife of 295,000 years, 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.
Standard atomic mass: 78.96(3) u

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Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
nuclide symbol	excitation energy			half-life	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
⁶⁵Se	34	31	64.96466(64)#	<50 ms	3/2-#
⁶⁶Se	34	32	65.95521(32)#	33(12) ms	0+
⁶⁷Se	34	33	66.95009(21)#	133(11) ms	5/2-#
⁶⁸Se	34	34	67.94180(4)	35.5(7) s	0+
⁶⁹Se	34	35	68.93956(4)	27.4(2) s	(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	0+
⁷¹Se	34	37	70.93224(3)	4.74(5) min	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	0+
⁷³Se	34	39	72.926765(11)	7.15(8) h	9/2+
^73mSe	25.71(4) keV			39.8(13) min	3/2-
⁷⁴Se	34	40	73.9224764(18)	STABLE	0+	0.0089(4)
⁷⁵Se	34	41	74.9225234(18)	119.779(4) d	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	7/2+
⁷⁸Se	34	44	77.9173091(18)	STABLE	0+	0.2377(28)
⁷⁹Se	34	45	78.9184991(18)	2.95(38)E+5 a	7/2+
^79mSe	95.77(3) keV			3.92(1) min	1/2-
⁸⁰Se	34	46	79.9165213(21)	STABLE	0+	0.4961(41)
⁸¹Se	34	47	80.9179925(22)	18.45(12) min	1/2-
^81mSe	102.99(6) keV			57.28(2) min	7/2+
⁸²Se	34	48	81.9166994(22)	97(5)E+18 a	0+	0.0873(22)
⁸³Se	34	49	82.919118(4)	22.3(3) min	9/2+
^83mSe	228.50(20) keV			70.1(4) s	1/2-
⁸⁴Se	34	50	83.918462(16)	3.1(1) min	0+
⁸⁵Se	34	51	84.92225(3)	31.7(9) s	(5/2+)#
⁸⁶Se	34	52	85.924272(17)	15.3(9) s	0+
⁸⁷Se	34	53	86.92852(4)	5.50(12) s	(5/2+)#
⁸⁸Se	34	54	87.93142(5)	1.53(6) s	0+
⁸⁹Se	34	55	88.93645(32)#	0.41(4) s	(5/2+)#
⁹⁰Se	34	56	89.93996(43)#	300# ms [>300 ns]	0+
⁹¹Se	34	57	90.94596(54)#	270(50) ms	1/2+#
⁹²Se	34	58	91.94992(64)#	100# ms [>300 ns]	0+
⁹³Se	34	59	92.95629(86)#	50# ms [>300 ns]	1/2+#
⁹⁴Se	34	60	93.96049(86)#	20# ms [>300 ns]	0+

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

Isotope masses from Ame2003 Atomic Mass Evaluation by G. Audi, A.H. Wapstra, C. Thibault, J. Blachot and O. Bersillon in Nuclear Physics A729 (2003).
Isotopic compositions and standard atomic masses from Atomic weights of the elements. Review 2000 (IUPAC Technical Report). Pure Appl. Chem. Vol. 75, No. 6, pp. 683-800, (2003) and Atomic Weights Revised (2005).
Half-life, spin, and isomer data selected from these sources. Editing notes on this article's talk page.
- Audi, Bersillon, Blachot, Wapstra. The Nubase2003 evaluation of nuclear and decay properties, Nuc. Phys. A 729, pp. 3-128 (2003).
- National Nuclear Data Center, Brookhaven National Laboratory. Information extracted from the NuDat 2.1 database (retrieved Sept. 2005).
- David R. Lide (ed.), Norman E. Holden in CRC Handbook of Chemistry and Physics, 85th Edition, online version. CRC Press. Boca Raton, Florida (2005). Section 11, Table of the Isotopes.

Isotopes of arsenic	Isotopes of selenium	Isotopes of bromine
Index to isotope pages

Categories: Isotopes | Selenium

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Isotopes_of_selenium". A list of authors is available in Wikipedia.