Isotopes of thulium

Isotopes of thulium (₆₉Tm)
Standard atomic weight Ar°(Tm)
	168.934219±0.000005; 168.93±0.01 (abridged);
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Naturally occurring thulium (₆₉Tm) is composed of one stable isotope, ¹⁶⁹Tm (100% natural abundance). Thirty-nine radioisotopes have been characterized, with the most stable being ¹⁷¹Tm with a half-life of 1.92 years, ¹⁷⁰Tm with a half-life of 128.6 days, ¹⁶⁸Tm with a half-life of 93.1 days, and ¹⁶⁷Tm with a half-life of 9.25 days. All of the remaining radioactive isotopes have half-lives that are less than 64 hours, and the majority of these have half-lives that are less than 2 minutes. This element also has 26 meta states, with the most stable being ^164mTm (t_1/2 5.1 minutes), ^160mTm (t_1/2 74.5 seconds) and ^155mTm (t_1/2 45 seconds).

The known isotopes of thulium range from ¹⁴⁴Tm to ¹⁸³Tm. The primary decay mode before the most abundant stable isotope, ¹⁶⁹Tm, is electron capture, and the primary mode after is beta emission. The primary decay products before ¹⁶⁹Tm are erbium isotopes, and the primary products after are ytterbium isotopes. All isotopes of thulium are either radioactive or, in the case of ¹⁶⁹Tm, observationally stable, meaning that ¹⁶⁹Tm is predicted to be radioactive but no actual decay has been observed.

List of isotopes

Nuclide ^{[n 1]}	Z	N	Isotopic mass (Da) ^{[n 2]}^{[n 3]}	Half-life ^{[n 4]}	Decay mode ^{[n 5]}	Daughter isotope ^{[n 6]}	Spin and parity ^{[n 7]}^{[n 4]}	Isotopic abundance
Nuclide ^{[n 1]}	Excitation energy^{[n 4]}			Half-life ^{[n 4]}	Decay mode ^{[n 5]}	Daughter isotope ^{[n 6]}	Spin and parity ^{[n 7]}^{[n 4]}	Isotopic abundance
¹⁴⁴Tm^[4]	69	75		1.9+1.2 −0.5 μs	p	¹⁴³Er	(10+)
¹⁴⁵Tm	69	76	144.97007(43)#	3.1(3) μs	p	¹⁴⁴Er	(11/2−)
¹⁴⁶Tm	69	77	145.96643(43)#	240(30) ms	p	¹⁴⁵Er	(6−)
¹⁴⁶Tm	69	77	145.96643(43)#	240(30) ms	β⁺ (rare)	¹⁴⁶Er	(6−)
^146mTm	71(6) keV			72(23) ms	p	¹⁴⁵Er	(10+)
^146mTm	71(6) keV			72(23) ms	β⁺ (rare)	¹⁴⁶Er	(10+)
¹⁴⁷Tm	69	78	146.96096(32)#	0.58(3) s	β⁺ (85%)	¹⁴⁷Er	11/2−
¹⁴⁷Tm	69	78	146.96096(32)#	0.58(3) s	p (15%)	¹⁴⁶Er	11/2−
^147mTm	60(5) keV			360(40) μs			3/2+
¹⁴⁸Tm	69	79	147.95784(43)#	0.7(2) s	β⁺	¹⁴⁸Er	(10+)
^148mTm				0.7 s
¹⁴⁹Tm	69	80	148.95272(32)#	0.9(2) s	β⁺ (99.74%)	¹⁴⁹Er	(11/2−)
¹⁴⁹Tm	69	80	148.95272(32)#	0.9(2) s	β⁺, p (.26%)	¹⁴⁸Ho	(11/2−)
¹⁵⁰Tm	69	81	149.94996(21)#	3# s	β⁺	¹⁵⁰Er	(1+)
^150m1Tm	140(140)# keV			2.20(6) s	β⁺ (98.8%)	¹⁵⁰Er	(6−)
^150m1Tm	140(140)# keV			2.20(6) s	β⁺, p (1.2%)	¹⁴⁹Ho	(6−)
^150m2Tm	810(140)# keV			5.2(3) ms			(10+)
¹⁵¹Tm	69	82	150.945483(22)	4.17(10) s	β⁺	¹⁵¹Er	(11/2−)
^151m1Tm	92(7) keV			6.6(14) s	β⁺	¹⁵¹Er	(1/2+)
^151m2Tm	2655.67(22) keV			451(24) ns			(27/2−)
¹⁵²Tm	69	83	151.94442(8)	8.0(10) s	β⁺	¹⁵²Er	(2#)−
^152m1Tm	100(80)# keV			5.2(6) s	β⁺	¹⁵²Er	(9)+
^152m2Tm	2555.05(19)+X keV			294(12) ns			(17+)
¹⁵³Tm	69	84	152.942012(20)	1.48(1) s	α (91%)	¹⁴⁹Ho	(11/2−)
¹⁵³Tm	69	84	152.942012(20)	1.48(1) s	β⁺ (9%)	¹⁵³Er	(11/2−)
^153mTm	43.2(2) keV			2.5(2) s	α (92%)	¹⁴⁹Ho	(1/2+)
^153mTm	43.2(2) keV			2.5(2) s	β⁺ (8%)	¹⁵³Er	(1/2+)
¹⁵⁴Tm	69	85	153.941568(15)	8.1(3) s	β⁺ (56%)	¹⁵⁴Er	(2−)
¹⁵⁴Tm	69	85	153.941568(15)	8.1(3) s	α (44%)	¹⁵⁰Ho	(2−)
^154mTm	70(50) keV			3.30(7) s	α (90%)	¹⁵⁰Ho	(9+)
^154mTm	70(50) keV			3.30(7) s	β⁺ (10%)	¹⁵⁴Er	(9+)
¹⁵⁵Tm	69	86	154.939199(14)	21.6(2) s	β⁺ (98.1%)	¹⁵⁵Er	(11/2−)
¹⁵⁵Tm	69	86	154.939199(14)	21.6(2) s	α (1.9%)	¹⁵¹Ho	(11/2−)
^155mTm	41(6) keV			45(3) s	β⁺ (92%)	¹⁵⁵Er	(1/2+)
^155mTm	41(6) keV			45(3) s	α (8%)	¹⁵¹Ho	(1/2+)
¹⁵⁶Tm	69	87	155.938980(17)	83.8(18) s	β⁺ (99.93%)	¹⁵⁶Er	2−
¹⁵⁶Tm	69	87	155.938980(17)	83.8(18) s	α (.064%)	¹⁵²Er	2−
^156mTm	203.6(5) keV			~400 ns			(11−)
¹⁵⁷Tm	69	88	156.93697(3)	3.63(9) min	β⁺	¹⁵⁷Er	1/2+
¹⁵⁸Tm	69	89	157.936980(27)	3.98(6) min	β⁺	¹⁵⁸Er	2−
^158mTm	50(100)# keV			~20 ns			(5+)
¹⁵⁹Tm	69	90	158.93498(3)	9.13(16) min	β⁺	¹⁵⁹Er	5/2+
¹⁶⁰Tm	69	91	159.93526(4)	9.4(3) min	β⁺	¹⁶⁰Er	1−
^160m1Tm	70(20) keV			74.5(15) s	IT (85%)	¹⁶⁰Tm	5(+#)
^160m1Tm	70(20) keV			74.5(15) s	β⁺ (15%)	¹⁶⁰Er	5(+#)
^160m2Tm	98.2+X keV			~200 ns			(8)
¹⁶¹Tm	69	92	160.93355(3)	30.2(8) min	β⁺	¹⁶¹Er	7/2+
^161m1Tm	7.4(2) keV			5# min			1/2+
^161m2Tm	78.20(3) keV			110(3) ns			7/2−
¹⁶²Tm	69	93	161.933995(28)	21.70(19) min	β⁺	¹⁶²Er	1−
^162mTm	130(40) keV			24.3(17) s	IT (82%)	¹⁶²Tm	5+
^162mTm	130(40) keV			24.3(17) s	β⁺ (18%)	¹⁶²Er	5+
¹⁶³Tm	69	94	162.932651(6)	1.810(5) h	β⁺	¹⁶³Er	1/2+
¹⁶⁴Tm	69	95	163.93356(3)	2.0(1) min	β⁺	¹⁶⁴Er	1+
^164mTm	10(6) keV			5.1(1) min	IT (80%)	¹⁶⁴Tm	6−
^164mTm	10(6) keV			5.1(1) min	β⁺ (20%)	¹⁶⁴Er	6−
¹⁶⁵Tm	69	96	164.932435(4)	30.06(3) h	β⁺	¹⁶⁵Er	1/2+
¹⁶⁶Tm	69	97	165.933554(13)	7.70(3) h	β⁺	¹⁶⁶Er	2+
^166mTm	122(8) keV			340(25) ms	IT	¹⁶⁶Tm	6−
¹⁶⁷Tm	69	98	166.9328516(29)	9.25(2) d	EC	¹⁶⁷Er	1/2+
^167m1Tm	179.480(19) keV			1.16(6) μs			(7/2)+
^167m2Tm	292.820(20) keV			0.9(1) μs			7/2−
¹⁶⁸Tm	69	99	167.934173(3)	93.1(2) d	β⁺ (99.99%)	¹⁶⁸Er	3+
¹⁶⁸Tm	69	99	167.934173(3)	93.1(2) d	β⁻ (.01%)	¹⁶⁸Yb	3+
¹⁶⁹Tm	69	100	168.9342133(27)	Observationally Stable^{[n 8]}			1/2+	1.0000
¹⁷⁰Tm	69	101	169.9358014(27)	128.6(3) d	β⁻ (99.86%)	¹⁷⁰Yb	1−
¹⁷⁰Tm	69	101	169.9358014(27)	128.6(3) d	EC (.14%)	¹⁷⁰Er	1−
^170mTm	183.197(4) keV			4.12(13) μs			(3)+
¹⁷¹Tm	69	102	170.9364294(28)	1.92(1) y	β⁻	¹⁷¹Yb	1/2+
^171mTm	424.9560(15) keV			2.60(2) μs			7/2−
¹⁷²Tm	69	103	171.938400(6)	63.6(2) h	β⁻	¹⁷²Yb	2−
¹⁷³Tm	69	104	172.939604(5)	8.24(8) h	β⁻	¹⁷³Yb	(1/2+)
^173mTm	317.73(20) keV			10(3) μs			(7/2−)
¹⁷⁴Tm	69	105	173.94217(5)	5.4(1) min	β⁻	¹⁷⁴Yb	(4)−
¹⁷⁵Tm	69	106	174.94384(5)	15.2(5) min	β⁻	¹⁷⁵Yb	(1/2+)
¹⁷⁶Tm	69	107	175.94699(11)	1.85(3) min	β⁻	¹⁷⁶Yb	(4+)
¹⁷⁷Tm	69	108	176.94904(32)#	90(6) s	β⁻	¹⁷⁷Yb	(7/2−)
¹⁷⁸Tm	69	109	177.95264(43)#	30# s	β⁻	¹⁷⁸Yb
¹⁷⁹Tm	69	110	178.95534(54)#	20# s	β⁻	¹⁷⁹Yb	1/2+#
¹⁸⁰Tm	69	111	179.95902(43)#	3# s	β⁻	¹⁸⁰Yb
¹⁸¹Tm	69	112	180.96195(54)#	7# s	β⁻	¹⁸¹Yb	1/2+#
¹⁸²Tm^[5]	69	113	181.96619(54)#
¹⁸³Tm^[5]	69	114
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Thulium-170

Thulium-170 has a half-life of 128.6 days, decaying by β⁻ decay about 99.87% of the time and electron capture the remaining 0.13% of the time.^[1] Due to its low-energy X-ray emissions, it has been proposed for radiotherapy^[6] and as a source in a radiothermal generator.^[7]

References

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
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.

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