Isotopes of thulium

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 (t1/2 5.1 minutes), 160mTm (t1/2 74.5 seconds) and 155mTm (t1/2 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

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

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. Due to its low-energy X-ray emissions, it has been proposed for radiotherapy and as a source in a radiothermal generator.