Isotopes of thulium

Naturally occurring thulium (Tm) is composed of 1 stable isotope, ¹⁶⁹Tm (100% natural abundance). Thirty-four 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 isotopes of thulium range in atomic weight from 144.97007 u (¹⁴⁵Tm) to 178.95534 u (¹⁷⁹Tm). 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.

Relative atomic mass: 168.93422(2).^[1]

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)[2][n 1]	daughter isotope(s)[n 2]	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
	excitation energy
^145Tm	69	76	144.97007(43)#	3.1(3) µs			(11/2−)
^146Tm	69	77	145.96643(43)#	240(30) ms	p	^145Er	(6−)
					β^+ (rare)	^146Er
^146mTm	71(6) keV			72(23) ms	p	^145Er	(10+)
					β^+ (rare)	^146Er
^147Tm	69	78	146.96096(32)#	0.58(3) s	β^+ (85%)	^147Er	11/2−
					p (15%)	^146Er
^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−)
					β^+, p (.26%)	^148Ho
^150Tm	69	81	149.94996(21)#	3# s	β^+	^150Er	(1+)
^150m1Tm	140(140)# keV			2.20(6) s	β^+ (98.8%)	^150Er	(6−)
					β^+, p (1.2%)	^149Ho
^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−)
					β^+ (9%)	^153Er
^153mTm	43.2(2) keV			2.5(2) s	α (92%)	^149Ho	(1/2+)
					β^+ (8%)	^153Er
^154Tm	69	85	153.941568(15)	8.1(3) s	β^+ (56%)	^154Er	(2−)
					α (44%)	^150Ho
^154mTm	70(50) keV			3.30(7) s	α (90%)	^150Ho	(9+)
					β^+ (10%)	^154Er
^155Tm	69	86	154.939199(14)	21.6(2) s	β^+ (98.1%)	^155Er	(11/2−)
					α (1.9%)	^151Ho
^155mTm	41(6) keV			45(3) s	β^+ (92%)	^155Er	(1/2+)
					α (8%)	^151Ho
^156Tm	69	87	155.938980(17)	83.8(18) s	β^+ (99.93%)	^156Er	2−
					α (.064%)	^152Er
^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(+#)
					β^+ (15%)	^160Er
^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+
					β^+ (18%)	^162Er
^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−
					β^+ (20%)	^164Er
^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+
					β^− (.01%)	^168Yb
^169Tm	69	100	168.9342133(27)	Observationally Stable[n 3]			1/2+	1.0000
^170Tm	69	101	169.9358014(27)	128.6(3) d	β^− (99.86%)	^170Yb	1−
					EC (.14%)	^170Er
^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+#

1. Abbreviations:
   EC: Electron capture
   IT: Isomeric transition
2. Bold for stable isotopes
3. Believed to undergo α decay to ¹⁶⁵Ho

Notes

• 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

1. Table of Standard Atomic Weights 2013 – CIAAW
2. "Universal Nuclide Chart". nucleonica. (registration required (help)).

• Isotope masses from:
  • G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001.
• 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; 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.
  • 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. 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; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001.
  • National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. 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 978-0-8493-0485-9.