Isotopes of erbium

Isotopes of erbium (₆₈Er)
Standard atomic weight Ar°(Er)
	167.259±0.003; 167.26±0.01 (abridged);
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Naturally occurring erbium (₆₈Er) is composed of six stable isotopes, with ¹⁶⁶Er being the most abundant (33.503% natural abundance). Thirty-nine radioisotopes have been characterized with between 74 and 112 neutrons, or 142 to 180 nucleons, with the most stable being ¹⁶⁹Er with a half-life of 9.4 days, ¹⁷²Er with a half-life of 49.3 hours, ¹⁶⁰Er with a half-life of 28.58 hours, ¹⁶⁵Er with a half-life of 10.36 hours, and ¹⁷¹Er with a half-life of 7.516 hours. All of the remaining radioactive isotopes have half-lives that are less than 3.5 hours, and the majority of these have half-lives that are less than 4 minutes. This element also has numerous meta states, with the most stable being ^167mEr (t_1/2 2.269 seconds).

The isotopes of erbium range in atomic weight from 141.9723 u (¹⁴²Er) to 179.9644 u (¹⁸⁰Er). The primary decay mode before the most abundant stable isotope, ¹⁶⁶Er, is electron capture, and the primary mode after is beta decay. The primary decay products before ¹⁶⁶Er are holmium isotopes, and the primary products after are thulium isotopes. All isotopes of erbium are either radioactive or observationally stable, meaning that they are predicted to be radioactive but no actual decay has been observed.

List of isotopes

Nuclide ^{[n 1]}	Z	N	Isotopic mass (Da)^[4] ^{[n 2]}^{[n 3]}	Half-life^[1] ^{[n 4]}	Decay mode^[1] ^{[n 5]}	Daughter isotope ^{[n 6]}	Spin and parity^[1] ^{[n 7]}^{[n 4]}	Natural abundance (mole fraction)
Nuclide ^{[n 1]}	Excitation energy^{[n 4]}			Half-life^[1] ^{[n 4]}	Decay mode^[1] ^{[n 5]}	Daughter isotope ^{[n 6]}	Spin and parity^[1] ^{[n 7]}^{[n 4]}	Normal proportion^[1]	Range of variation
¹⁴²Er	68	74	141.97002(54)#	10# μみゅーs	p	¹⁴¹Ho	0+
¹⁴³Er	68	75	142.96655(43)#	200# ms	βべーた⁺	¹⁴³Ho	9/2−#
¹⁴³Er	68	75	142.96655(43)#	200# ms	βべーた⁺, p	¹⁴²Dy	9/2−#
¹⁴⁴Er	68	76	143.96070(21)#	400# ms [>200 ns]	βべーた⁺	¹⁴⁴Ho	0+
¹⁴⁵Er	68	77	144.95787(22)#	900(200) ms	βべーた⁺	¹⁴⁵Ho	1/2+#
¹⁴⁵Er	68	77	144.95787(22)#	900(200) ms	βべーた⁺, p (rare)	¹⁴⁴Dy	1/2+#
^145mEr	205(4)# keV			1.0(3) s	βべーた⁺	¹⁴⁵Ho	(11/2-)
					IT (rare)	¹⁴⁵Er
					βべーた⁺, p (rare)	¹⁴⁴Dy
¹⁴⁶Er	68	78	145.952418(7)	1.7(6) s	βべーた⁺	¹⁴⁶Ho	0+
¹⁴⁶Er	68	78	145.952418(7)	1.7(6) s	βべーた⁺, p (rare)	¹⁴⁵Dy	0+
¹⁴⁷Er	68	79	146.94996(4)#	3.2(1.2) s	βべーた⁺	¹⁴⁷Ho	(1/2+)
¹⁴⁷Er	68	79	146.94996(4)#	3.2(1.2) s	βべーた⁺, p (rare)	¹⁴⁶Dy	(1/2+)
^147mEr	100(50)# keV			1.6(2) s	βべーた⁺	¹⁴⁷Ho	(11/2−)
^147mEr	100(50)# keV			1.6(2) s	βべーた⁺, p (rare)	¹⁴⁶Dy	(11/2−)
¹⁴⁸Er	68	80	147.944735(11)#	4.6(2) s	βべーた⁺ (99.85%)	¹⁴⁸Ho	0+
¹⁴⁸Er	68	80	147.944735(11)#	4.6(2) s	βべーた⁺, p (.15%)	¹⁴⁷Dy	0+
^148mEr	2.9132(4) MeV			13(3) μみゅーs	IT	¹⁴⁸Er	(10+)
¹⁴⁹Er	68	81	148.94231(3)	4(2) s	βべーた⁺ (92.8%)	¹⁴⁹Ho	(1/2+)
¹⁴⁹Er	68	81	148.94231(3)	4(2) s	βべーた⁺, p (7.2%)	¹⁴⁸Dy	(1/2+)
^149m1Er	741.8(2) keV			8.9(2) s	βべーた⁺ (96.5%)	¹⁴⁹Ho	(11/2−)
					IT (3.5%)	¹⁴⁹Er
					βべーた⁺, p (.18%)	¹⁴⁸Dy
^149m2Er	2.6111(3) MeV			0.61(8) μみゅーs	IT	¹⁴⁹Er	(19/2+)
^149m3Er	3.302(7) MeV			4.8(1) μみゅーs	IT	¹⁴⁹Er	(27/2−)
¹⁵⁰Er	68	82	149.937916(18)	18.5(7) s	βべーた⁺	¹⁵⁰Ho	0+
^150mEr	2.7965(5) MeV			2.55(10) μみゅーs	IT	¹⁵⁰Er	10+
¹⁵¹Er	68	83	150.937449(18)	23.5(20) s	βべーた⁺	¹⁵¹Ho	(7/2−)
^151m1Er	2.5860(5) MeV			580(20) ms	IT (95.3%)	¹⁵¹Er	(27/2−)
^151m1Er	2.5860(5) MeV			580(20) ms	βべーた⁺ (4.7%)	¹⁵¹Ho	(27/2−)
^151m2Er	10.2866(10) MeV			0.42(5) μみゅーs	IT	¹⁵¹Er	(65/2-, 61/2+)
¹⁵²Er	68	84	151.935050(9)	10.3(1) s	αあるふぁ (90%)	¹⁴⁸Dy	0+
¹⁵²Er	68	84	151.935050(9)	10.3(1) s	βべーた⁺ (10%)	¹⁵²Ho	0+
¹⁵³Er	68	85	152.935086(10)	37.1(2) s	αあるふぁ (53%)	¹⁴⁹Dy	7/2(−)
¹⁵³Er	68	85	152.935086(10)	37.1(2) s	βべーた⁺ (47%)	¹⁵³Ho	7/2(−)
^153m1Er	2.7982(10) MeV			373(9) ns	IT	¹⁵³Er	(27/2-)
^153m2Er	5.2481(10) MeV			248(32) ns	IT	¹⁵³Er	(41/2-)
¹⁵⁴Er	68	86	153.932791(5)	3.73(9) min	βべーた⁺ (99.53%)	¹⁵⁴Ho	0+
¹⁵⁴Er	68	86	153.932791(5)	3.73(9) min	αあるふぁ (.47%)	¹⁵⁰Dy	0+
¹⁵⁵Er	68	87	154.933216(7)	5.3(3) min	βべーた⁺ (99.978%)	¹⁵⁵Ho	7/2−
¹⁵⁵Er	68	87	154.933216(7)	5.3(3) min	αあるふぁ (.022%)	¹⁵¹Dy	7/2−
¹⁵⁶Er	68	88	155.931066(26)	19.5(10) min	βべーた⁺	¹⁵⁶Ho	0+
¹⁵⁶Er	68	88	155.931066(26)	19.5(10) min	αあるふぁ (1.2×10⁻⁵%)	¹⁵²Dy	0+
¹⁵⁷Er	68	89	156.931923(28)	18.65(10) min	βべーた⁺	¹⁵⁷Ho	3/2−
^157mEr	155.4(3) keV			76(6) ms	IT	¹⁵⁷Er	(9/2+)
¹⁵⁸Er	68	90	157.929893(27)	2.29(6) h	EC	¹⁵⁸Ho	0+
¹⁵⁹Er	68	91	158.930691(4)	36(1) min	βべーた⁺	¹⁵⁹Ho	3/2−
^159m1Er	182.602(24) keV			337(14) ns	IT	¹⁵⁹Er	9/2+
^159m2Er	429.05(3) keV			590(60) ns	IT	¹⁵⁹Er	11/2−
¹⁶⁰Er	68	92	159.929077(26)	28.58(9) h	EC	¹⁶⁰Ho	0+
¹⁶¹Er	68	93	160.930004(9)	3.21(3) h	βべーた⁺	¹⁶¹Ho	3/2−
^161mEr	396.44(4) keV			7.5(7) μみゅーs	IT	¹⁶¹Er	11/2−
¹⁶²Er	68	94	161. 9287873(8)	Observationally Stable^{[n 8]}			0+	0.00139(5)
^162mEr	2.02601(13) MeV			88(16) ns	IT	¹⁶²Er	(7-)
¹⁶³Er	68	95	162.930040(5)	75.0(4) min	βべーた⁺	¹⁶³Ho	5/2−
^163mEr	445.5(6) keV			580(100) ns	IT	¹⁶³Er	(11/2−)
¹⁶⁴Er	68	96	163.9292077(8)	Observationally Stable^{[n 9]}			0+	0.01601(3)
¹⁶⁵Er	68	97	164.9307335(10)	10.36(4) h	EC	¹⁶⁵Ho	5/2−
^165m1Er	551.3(6) keV			250(30)ns	IT	¹⁶⁵Er	11/2-
^165m2Er	1.8230(6) MeV			370(40)ns	IT	¹⁶⁵Er	(19/2)
¹⁶⁶Er	68	98	165.9303011(4)	Observationally Stable^{[n 10]}			0+	0.33503(36)
¹⁶⁷Er	68	99	166.9320562(3)	Observationally Stable^{[n 11]}			7/2+	0.22869(9)
^167mEr	207.801(5) keV			2.269(6) s	IT	¹⁶⁷Er	1/2−
¹⁶⁸Er	68	100	167.93237828(28)	Observationally Stable^{[n 12]}			0+	0.26978(18)
^168mEr	1.0940383(16) MeV			109.0(7) ns	IT	¹⁶⁸Er	4-
¹⁶⁹Er	68	101	168.9345984(3)	9.392(18) d	βべーた⁻	¹⁶⁹Tm	1/2−
^169m1Er	92.05(10) keV			285(20) ns	IT	¹⁶⁹Er	(5/2-)
^169m2Er	243.69(17) keV			200(10) ns	IT	¹⁶⁹Er	7/2+
¹⁷⁰Er	68	102	169.9354719(15)	Observationally Stable^{[n 13]}			0+	0.14910(36)
¹⁷¹Er	68	103	170.93803746(15)	7.516(2) h	βべーた⁻	¹⁷¹Tm	5/2−
^171mEr	198.61(9) keV\|			210(10) ns	IT	¹⁷¹Er	1/2−
¹⁷²Er	68	104	171.939363(4)	49.3(5) h	βべーた⁻	¹⁷²Tm	0+
^172mEr	1.5009(3) MeV			579(62) ns	IT	¹⁷²Er	(6+)
¹⁷³Er	68	105	172.94240(21)#	1.434(17) min	βべーた⁻	¹⁷³Tm	(7/2−)
¹⁷⁴Er	68	106	173.94423(32)#	3.2(2) min	βべーた⁻	¹⁷⁴Tm	0+
^174mEr	1.1115(7) MeV			3.9(3) s	IT	¹⁷⁴Er	8-
¹⁷⁵Er	68	107	174.94777(43)#	1.2(3) min	βべーた⁻	¹⁷⁵Tm	9/2+#
¹⁷⁶Er	68	108	175.94994(43)#	12# s (>300 ns)	βべーた⁻	¹⁷⁶Tm	0+
¹⁷⁷Er	68	109	176.95399(54)#	8# s (>300 ns)	βべーた⁻	¹⁷⁷Tm	1/2−#
¹⁷⁸Er	68	110	177.95678(64)#	4# s (>300 ns)	βべーた⁻	¹⁷⁸Tm	0+
¹⁷⁹Er	68	111	178.96127(54)#	3# s (>550 ns)	βべーた⁻	¹⁷⁹Tm	3/2−#
¹⁷⁹Er	68	111	178.96127(54)#	3# s (>550 ns)	βべーた⁻, n	¹⁷⁸Tm	3/2−#
¹⁸⁰Er	68	112	179.96438(54)#	2# s (>550 ns)	βべーた⁻	¹⁸⁰Tm	0+
¹⁸⁰Er	68	112	179.96438(54)#	2# s (>550 ns)	βべーた⁻, n	¹⁷⁹Tm	0+
This table header & footer: view

^ ^mEr – Excited nuclear isomer.
^ ( ) – Uncertainty (1σしぐま) 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).
^ ^a ^b ^c # – 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

p: Proton emission
^ Bold symbol as daughter – Daughter product is stable.
^ ( ) spin value – Indicates spin with weak assignment arguments.
^ Believed to undergo αあるふぁ decay to ¹⁵⁸Dy or βべーた⁺βべーた⁺ to ¹⁶²Dy with a half-life over 140×10¹² years
^ Believed to undergo αあるふぁ decay to ¹⁶⁰Dy or βべーた⁺βべーた⁺ to ¹⁶⁴Dy
^ Believed to undergo αあるふぁ decay to ¹⁶²Dy
^ Believed to undergo αあるふぁ decay to ¹⁶³Dy
^ Believed to undergo αあるふぁ decay to ¹⁶⁴Dy
^ Believed to undergo αあるふぁ decay to ¹⁶⁶Dy or βべーた⁻βべーた⁻ to ¹⁷⁰Yb with a half-life over 410×10¹⁵ years

References

^ ^a ^b ^c ^d ^e 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: Erbium". CIAAW. 1999.
^ 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.
^ Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.

Isotope masses from:
- Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.
Isotopic compositions and standard atomic masses from:
- 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.
- 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.
- 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.
- 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.

[4] Er – Excited nuclear isomer.

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

[TMS-7] # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).

[TNN-8] # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).

[9] Modes of decay:

EC: Electron capture

IT: Isomeric transition

p: Proton emission

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

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

[12] Believed to undergo αあるふぁ decay to ¹⁵⁸Dy or βべーた⁺βべーた⁺ to ¹⁶²Dy with a half-life over 140×10¹² years

[13] Believed to undergo αあるふぁ decay to ¹⁶⁰Dy or βべーた⁺βべーた⁺ to ¹⁶⁴Dy

[14] Believed to undergo αあるふぁ decay to ¹⁶²Dy

[15] Believed to undergo αあるふぁ decay to ¹⁶³Dy

[16] Believed to undergo αあるふぁ decay to ¹⁶⁴Dy

[17] Believed to undergo αあるふぁ decay to ¹⁶⁶Dy or βべーた⁻βべーた⁻ to ¹⁷⁰Yb with a half-life over 410×10¹⁵ years

[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: Erbium". CIAAW. 1999.

[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.

[AME2020_II-5] Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.

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