Isotopes of thulium

Naturally occurring thulium (₆₉Tm) is composed of one 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).

Main isotopes of thulium (₆₉Tm)

Iso­tope Decay abun­dance half-life (t1/2) mode pro­duct ^167Tm syn 9.25 d ε ^167Er ^168Tm syn 93.1 d ε ^168Er ^169Tm 100% stable ^170Tm syn 128.6 d β^− ^170Yb ^171Tm syn 1.92 y β^− ^171Yb
Standard atomic weight Ar, standard(Tm)	168.93422(2)[1]

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.

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]	Natural abundance (mole fraction)
	Excitation energy[n 4]							Normal proportion	Range of variation
^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 8]			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. ^mTm – 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. Believed to undergo α decay to ¹⁶⁵Ho

References

1. Meija, Juris; et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry. 88 (3): 265–91. doi:10.1515/pac-2015-0305.

• 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
• Isotopic compositions and standard atomic masses from:
  • 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. Lay summary.
• 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.