Isotopes of erbium

Naturally occurring erbium (₆₈Er) is composed of six stable isotopes, with ¹⁶⁶Er being the most abundant (33.503% natural abundance). Radioisotopes have been characterized with from ¹⁴⁵Er to ¹⁷⁵Er, all having half-lives less than ten days: the most stable are ¹⁶⁹Er (9.39 days), ¹⁷²Er (49.3 hours), and ¹⁶⁰Er (28.58 hours). All of the remaining radioactive isotopes have half-lives that are less than 11 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 ^149m1Er (t_1/2 = 8.9 seconds).

Quick facts Main isotopes, Decay ...

Isotopes of erbium (₆₈Er)

Main isotopes^[1]			Decay
Isotope	abundance	half-life (t_1/2)	mode	product
¹⁶²Er	0.139%	stable
¹⁶⁴Er	1.60%	stable
¹⁶⁵Er	synth	10.36 h	ε	¹⁶⁵Ho
¹⁶⁶Er	33.5%	stable
¹⁶⁷Er	22.9%	stable
¹⁶⁸Er	27.0%	stable
¹⁶⁹Er	synth	9.39 d	β⁻	¹⁶⁹Tm
¹⁷⁰Er	14.9%	stable

Standard atomic weight A_r°(Er)

167.259±0.003^[2]
167.26±0.01 (abridged)^[3]

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The primary decay mode before the most abundant stable isotope, ¹⁶⁶Er, is electron capture to holmium isotopes, and the primary mode after is beta decay to 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

More information Nuclide, Z ...

Nuclide ^{[n 1]}	Z	N	Isotopic mass (Da)^[4] ^{[n 2]}^{[n 3]}	Discovery year^[5]^[6]	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]}			Discovery year^[5]^[6]	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
¹⁴³Er	68	75	142.96655(43)#	2026	200# ms			9/2−#
¹⁴⁴Er	68	76	143.96070(21)#	2003	400# ms [> 200 ns]			0+
¹⁴⁵Er	68	77	144.95787(22)#	1989	900(200) ms	β⁺	¹⁴⁵Ho	1/2+#
¹⁴⁵Er	68	77	144.95787(22)#	1989	900(200) ms	β⁺, p (?%)	¹⁴⁴Dy	1/2+#
^145mEr	205(4)# keV			2003	1.0(3) s	β⁺	¹⁴⁵Ho	(11/2-)
^145mEr	205(4)# keV			2003	1.0(3) s	β⁺, p (?%)	¹⁴⁴Dy	(11/2-)
¹⁴⁶Er	68	78	145.952418(7)	1993	1.7(6) s	β⁺	¹⁴⁶Ho	0+
¹⁴⁶Er	68	78	145.952418(7)	1993	1.7(6) s	β⁺, p (?%)	¹⁴⁵Dy	0+
¹⁴⁷Er	68	79	146.94996(4)#	1992	3.2(12) s	β⁺	¹⁴⁷Ho	(1/2+)
¹⁴⁷Er	68	79	146.94996(4)#	1992	3.2(12) s	β⁺, p (?%)	¹⁴⁶Dy	(1/2+)
^147mEr^{[n 8]}	100(50)# keV			2010	1.6(2) s	β⁺	¹⁴⁷Ho	(11/2−)
^147mEr^{[n 8]}	100(50)# keV			2010	1.6(2) s	β⁺, p (?%)	¹⁴⁶Dy	(11/2−)
¹⁴⁸Er	68	80	147.944735(11)#	1982	4.6(2) s	β⁺ (99.85%)	¹⁴⁸Ho	0+
¹⁴⁸Er	68	80	147.944735(11)#	1982	4.6(2) s	β⁺, p (0.15%)	¹⁴⁷Dy	0+
^148mEr	2913,2(4) keV			1982	13(3) μs	IT	¹⁴⁸Er	(10+)
¹⁴⁹Er	68	81	148.94231(3)	1984	4(2) s	β⁺ (93%)	¹⁴⁹Ho	(1/2+)
¹⁴⁹Er	68	81	148.94231(3)	1984	4(2) s	β⁺, p (7%)	¹⁴⁸Dy	(1/2+)
^149m1Er	741.8(2) keV			1985	8.9(2) s	β⁺ (96.3%)	¹⁴⁹Ho	(11/2−)
						IT (3.5%)	¹⁴⁹Er
						β⁺, p (0.18%)	¹⁴⁸Dy
^149m2Er	2611.1(3) keV			1987	0.61(8) μs	IT	¹⁴⁹Er	(19/2+)
^149m3Er	3302(7) keV			1987	4.8(1) μs	IT	¹⁴⁹Er	(27/2−)
¹⁵⁰Er	68	82	149.937916(18)	1982	18.5(7) s	β⁺	¹⁵⁰Ho	0+
^150mEr	2796.5(5) keV			1982	2.55(10) μs	IT	¹⁵⁰Er	10+
¹⁵¹Er	68	83	150.937449(18)	1970	23.5(20) s	β⁺	¹⁵¹Ho	(7/2−)
^151m1Er	2586.0(5) keV			1980	580(20) ms	IT (95.3%)	¹⁵¹Er	(27/2−)
^151m1Er	2586.0(5) keV			1980	580(20) ms	β⁺ (4.7%)	¹⁵¹Ho	(27/2−)
^151m2Er	10286.6(10) keV			1990	0.42(5) μs	IT	¹⁵¹Er	(65/2-, 61/2+)
¹⁵²Er	68	84	151.935050(9)	1963	10.3(1) s	α (90%)	¹⁴⁸Dy	0+
¹⁵²Er	68	84	151.935050(9)	1963	10.3(1) s	β⁺ (10%)	¹⁵²Ho	0+
¹⁵³Er	68	85	152.935086(10)	1963	37.1(2) s	α (53%)	¹⁴⁹Dy	7/2−
¹⁵³Er	68	85	152.935086(10)	1963	37.1(2) s	β⁺ (47%)	¹⁵³Ho	7/2−
^153m1Er	2798.2(10) keV			1979	373(9) ns	IT	¹⁵³Er	(27/2-)
^153m2Er	5248.1(10) keV			1980	248(32) ns	IT	¹⁵³Er	(41/2-)
¹⁵⁴Er	68	86	153.932791(5)	1963	3.73(9) min	β⁺ (99.53%)	¹⁵⁴Ho	0+
¹⁵⁴Er	68	86	153.932791(5)	1963	3.73(9) min	α (0.47%)	¹⁵⁰Dy	0+
¹⁵⁵Er	68	87	154.933216(7)	1969	5.3(3) min	β⁺ (99.978%)	¹⁵⁵Ho	7/2−
¹⁵⁵Er	68	87	154.933216(7)	1969	5.3(3) min	α (0.022%)	¹⁵¹Dy	7/2−
¹⁵⁶Er	68	88	155.931066(26)	1967	19.5(10) min	β⁺	¹⁵⁶Ho	0+
¹⁵⁶Er	68	88	155.931066(26)	1967	19.5(10) min	α (1.2×10⁻⁵%)	¹⁵²Dy	0+
¹⁵⁷Er	68	89	156.931923(28)	1965	18.65(10) min	β⁺	¹⁵⁷Ho	3/2−
^157mEr	155.4(3) keV			(1971)^{[n 9]}	76(6) ms	IT	¹⁵⁷Er	9/2+
¹⁵⁸Er	68	90	157.929893(27)	1960	2.29(6) h	EC	¹⁵⁸Ho	0+
¹⁵⁹Er	68	91	158.930691(4)	1961	36(1) min	β⁺	¹⁵⁹Ho	3/2−
^159m1Er	182.602(24) keV			1975	337(14) ns	IT	¹⁵⁹Er	9/2+
^159m2Er	429.05(3) keV			1975	590(60) ns	IT	¹⁵⁹Er	11/2−
¹⁶⁰Er	68	92	159.929077(26)	1954	28.58(9) h	EC	¹⁶⁰Ho	0+
¹⁶¹Er	68	93	160.930004(9)	1954	3.21(3) h	β⁺	¹⁶¹Ho	3/2−
^161mEr	396.44(4) keV			1969	7.5(7) μs	IT	¹⁶¹Er	11/2−
¹⁶²Er	68	94	161.9287873(8)	1938	Observationally Stable^{[n 10]}			0+	0.00139(5)
^162mEr	2026.01(13) keV			(2012)^{[n 11]}	88(16) ns	IT	¹⁶²Er	7(-)
¹⁶³Er	68	95	162.930040(5)	1953	75.0(4) min	β⁺	¹⁶³Ho	5/2−
^163mEr	445.5(6) keV			1970	580(100) ns	IT	¹⁶³Er	(11/2−)
¹⁶⁴Er	68	96	163.9292077(8)	1938	Observationally Stable^{[n 12]}			0+	0.01601(3)
¹⁶⁵Er	68	97	164.9307335(10)	1950	10.36(4) h	EC	¹⁶⁵Ho	5/2−
^165m1Er	551.3(6) keV			1974	250(30) ns	IT	¹⁶⁵Er	11/2-
^165m2Er	1823.0(6) keV			2012	370(40) ns	IT	¹⁶⁵Er	(19/2)
¹⁶⁶Er	68	98	165.9303011(4)	1934	Observationally Stable^{[n 13]}			0+	0.33503(36)
¹⁶⁷Er	68	99	166.9320562(3)	1934	Observationally Stable^{[n 14]}			7/2+	0.22869(9)
^167mEr	207.801(5) keV			1963	2.269(6) s	IT	¹⁶⁷Er	1/2−
¹⁶⁸Er	68	100	167.93237828(28)	1934	Observationally Stable^{[n 15]}			0+	0.26978(18)
^168mEr	1094.0383(16) keV			1957	109.0(7) ns	IT	¹⁶⁸Er	4-
¹⁶⁹Er	68	101	168.9345984(3)	1956	9.392(18) d	β⁻	¹⁶⁹Tm	1/2−
^169m1Er	92.05(10) keV			(1969)^{[n 9]}	285(20) ns	IT	¹⁶⁹Er	(5/2)-
^169m2Er	243.69(17) keV			(1969)^{[n 9]}	200(10) ns	IT	¹⁶⁹Er	7/2+
¹⁷⁰Er	68	102	169.9354719(15)	1934	Observationally Stable^{[n 16]}			0+	0.14910(36)
¹⁷¹Er	68	103	170.9380374(15)	1938	7.516(2) h	β⁻	¹⁷¹Tm	5/2−
^171mEr	198.61(9) keV			1990	210(10) ns	IT	¹⁷¹Er	1/2−
¹⁷²Er	68	104	171.939363(4)	1956	49.3(5) h	β⁻	¹⁷²Tm	0+
^172mEr	1500,9(3) keV			2006	579(62) ns	IT	¹⁷²Er	(6+)
¹⁷³Er	68	105	172.94240(21)#	1972	1.434(17) min	β⁻	¹⁷³Tm	(7/2−)
¹⁷⁴Er	68	106	173.94423(32)#	1989	3.2(2) min	β⁻	¹⁷⁴Tm	0+
^174mEr	1111.5(7) keV			2006	3.9(3) s	IT	¹⁷⁴Er	8-
¹⁷⁵Er	68	107	174.94777(43)#	1996	1.2(3) min	β⁻	¹⁷⁵Tm	9/2+#
¹⁷⁶Er	68	108	175.94994(43)#	2012	12# s [>300 ns]			0+
¹⁷⁷Er	68	109	176.95399(54)#	2012	8# s [>300 ns]			1/2−#
¹⁷⁸Er	68	110	177.95678(64)#	2012	4# s [>300 ns]			0+
¹⁷⁹Er	68	111	178.96127(54)#	2018	3# s [>550 ns)]			3/2−#
¹⁸⁰Er	68	112	179.96438(54)#	2018	2# s [>550 ns]			0+
This table header & footer: view

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[1]
^mEr – Excited nuclear isomer.
[2]
( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
[3]
# – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
[4]
# – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
[5]
Modes of decay:

EC: Electron capture

IT: Isomeric transition

p: Proton emission
[6]
Bold symbol as daughter – Daughter product is stable.
[7]
( ) spin value – Indicates spin with weak assignment arguments.
[8]
Order of ground state and isomer is uncertain.
[9]
Only published in a conference proceeding and not a refereed journal.
[10]
Believed to undergo α decay to ¹⁵⁸Dy or β⁺β⁺ to ¹⁶²Dy with a half-life over 1.40×10¹⁴ years
[11]
Half-life shorter than 100ns, not included in discovery database
[12]
Believed to undergo α decay to ¹⁶⁰Dy or β⁺β⁺ to ¹⁶⁴Dy
[13]
Believed to undergo α decay to ¹⁶²Dy
[14]
Believed to undergo α decay to ¹⁶³Dy
[15]
Believed to undergo α decay to ¹⁶⁴Dy
[16]
Believed to undergo α decay to ¹⁶⁶Dy or β⁻β⁻ to ¹⁷⁰Yb with a half-life over 4.10×10¹⁷ years

Isotopes of erbium

List of isotopes

See also

References

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