Isotopes of terbium explained

Naturally occurring terbium (₆₅Tb) is composed of one stable isotope, ¹⁵⁹Tb. Thirty-seven radioisotopes have been characterized, with the most stable being ¹⁵⁸Tb with a half-life of 180 years, ¹⁵⁷Tb with a half-life of 71 years, and ¹⁶⁰Tb with a half-life of 72.3 days. All of the remaining radioactive isotopes have half-lives that are less than 6.907 days, and the majority of these have half-lives that are less than 24 seconds. This element also has 27 meta states, with the most stable being ^156m1Tb (t_1/2 = 24.4 hours), ^154m2Tb (t_1/2 = 22.7 hours) and ^154m1Tb (t_1/2 = 9.4 hours).

The primary decay mode before the most abundant stable isotope, ¹⁵⁹Tb, is electron capture, and the primary mode behind is beta decay. The primary decay products before ¹⁵⁹Tb are element Gd (gadolinium) isotopes, and the primary products after ¹⁵⁹Tb are element Dy (dysprosium) isotopes.

List of isotopes

|-id=Terbium-135| ¹³⁵Tb| style="text-align:right" | 65| style="text-align:right" | 70| 134.96452(43)#| 1.01(28) ms| p| ¹³⁴Gd| (7/2−)||-id=Terbium-139| ¹³⁹Tb| style="text-align:right" | 65| style="text-align:right" | 74| 138.94833(32)#| 1.6(2) s| β⁺| ¹³⁹Gd| 5/2−#||-id=Terbium-140| rowspan=3|¹⁴⁰Tb| rowspan=3 style="text-align:right" | 65| rowspan=3 style="text-align:right" | 75| rowspan=3|139.94581(86)| rowspan=3|2.29(15) s| β⁺ (99.74%)| ¹⁴⁰Gd| rowspan=3|(7+)| rowspan=3||-| EC (<3%)| ¹⁴⁰Gd|-| β⁺, p (0.26%)| ¹³⁹Eu|-id=Terbium-141| ¹⁴¹Tb| style="text-align:right" | 65| style="text-align:right" | 76| 140.94145(11)| 3.5(2) s| β⁺| ¹⁴¹Gd| (5/2−)||-id=Terbium-141m| style="text-indent:1em" | ^141mTb^[1] ^[2] | colspan="3" style="text-indent:2em" | 0(200)# keV| 7.9(6) s| β⁺| ¹⁴¹Gd| 11/2−#||-id=Terbium-142| rowspan=3|¹⁴²Tb| rowspan=3 style="text-align:right" | 65| rowspan=3 style="text-align:right" | 77| rowspan=3|141.93928(75)| rowspan=3|597(17) ms| β⁺ (96.8%)| ¹⁴²Gd| rowspan=3|1+| rowspan=3||-| EC (3.2%)| ¹⁴²Gd|-| β⁺, p (0.0022%)| ¹⁴¹Eu|-id=Terbium-142m1| style="text-indent:1em" | ^142m1Tb| colspan="3" style="text-indent:2em" | 279.7(4) keV| 303(17) ms| IT| ¹⁴²Tb| 5−| |-id=Terbium-142m2| style="text-indent:1em" | ^142m2Tb| colspan="3" style="text-indent:2em" | 652.1(6) keV| 26(1) μs| IT| ¹⁴²Tb| 8+||-id=Terbium-143| ¹⁴³Tb| style="text-align:right" | 65| style="text-align:right" | 78| 142.935137(55)| 12(1) s| β⁺| ¹⁴³Gd| (11/2−)||-id=Terbium-143m| style="text-indent:1em" | ^143mTb^[1] | colspan="3" style="text-indent:2em" | 0(100)# keV| 17(4) s| | | 5/2+#||-id=Terbium-144| ¹⁴⁴Tb| style="text-align:right" | 65| style="text-align:right" | 79| 143.933045(30)| ~1 s| β⁺| ¹⁴⁴Gd| 1+| |-id=Terbium-144m1| rowspan=2 style="text-indent:1em" | ^144m1Tb| rowspan=2 colspan="3" style="text-indent:2em" | 396.9(5) keV| rowspan=2|4.25(15) s| IT (66%)| ¹⁴⁴Tb| rowspan=2|6−| rowspan=2||-| β⁺ (34%)| ¹⁴⁴Gd|-id=Terbium-144m2| style="text-indent:1em" | ^144m2Tb| colspan="3" style="text-indent:2em" | 476.2(5) keV| 2.8(3) μs| IT| ¹⁴⁴Tb| (8−)||-id=Terbium-144m3| style="text-indent:1em" | ^144m3Tb| colspan="3" style="text-indent:2em" | 517.1(5) keV| 670(60) ns| IT| ¹⁴⁴Tb| (9+)||-id=Terbium-144m4| style="text-indent:1em" | ^144m4Tb| colspan="3" style="text-indent:2em" | 544.5(6) keV| <300 ns| IT| ¹⁴⁴Tb| (10+)||-id=Terbium-145| ¹⁴⁵Tb| style="text-align:right" | 65| style="text-align:right" | 80| 144.92872(12)| 30.9(6) s| β⁺| ¹⁴⁵Gd| (11/2−)||-id=Terbium-145m| style="text-indent:1em" | ^145mTb^[1] | colspan="3" style="text-indent:2em" | 860(230) keV| | | | (3/2+)||-id=Terbium-146| ¹⁴⁶Tb| style="text-align:right" | 65| style="text-align:right" | 81| 145.927253(48)| 8(4) s| β⁺| ¹⁴⁶Gd| 1+||-id=Terbium-146m1| style="text-indent:1em" | ^146m1Tb^[1] | colspan="3" style="text-indent:2em" | 150(100)# keV| 24.1(5) s| β⁺| ¹⁴⁶Gd| 5−||-id=Terbium-146m2| style="text-indent:1em" | ^146m2Tb| colspan="3" style="text-indent:2em" | 930(100)# keV| 1.18(2) ms| IT| ¹⁴⁶Tb| 10+||-id=Terbium-147| ¹⁴⁷Tb| style="text-align:right" | 65| style="text-align:right" | 82| 146.9240546(87)| 1.64(3) h| β⁺| ¹⁴⁷Gd| (1/2+)||-id=Terbium-147m| style="text-indent:1em" | ^147mTb| colspan="3" style="text-indent:2em" | 50.6(9) keV| 1.87(5) min| β⁺| ¹⁴⁷Gd| (11/2−)||-id=Terbium-148| ¹⁴⁸Tb| style="text-align:right" | 65| style="text-align:right" | 83| 147.924275(13)| 60(1) min| β⁺| ¹⁴⁸Gd| 2−||-id=Terbium-148m1| style="text-indent:1em" | ^148m1Tb| colspan="3" style="text-indent:2em" | 90.1(3) keV| 2.20(5) min| β⁺| ¹⁴⁸Gd| (9)+||-id=Terbium-148m2| style="text-indent:1em" | ^148m2Tb| colspan="3" style="text-indent:2em" | 8618.6(10) keV| 1.310(7) μs| IT| ¹⁴⁸Tb| (27+)||-id=Terbium-149| rowspan=2|¹⁴⁹Tb| rowspan=2 style="text-align:right" | 65| rowspan=2 style="text-align:right" | 84| rowspan=2|148.9232538(39)| rowspan=2|4.118(25) h| β⁺ (83.3%)| ¹⁴⁹Gd| rowspan=2|1/2+| rowspan=2||-| α (16.7%)| ¹⁴⁵Eu|-id=Terbium-149m| rowspan=2 style="text-indent:1em" | ^149mTb| rowspan=2 colspan="3" style="text-indent:2em" | 35.78(13) keV| rowspan=2|4.16(4) min| β⁺ (99.98%)| ¹⁴⁹Gd| rowspan=2|11/2−| rowspan=2||-| α (0.022%)| ¹⁴⁵Eu|-id=Terbium-150| ¹⁵⁰Tb| style="text-align:right" | 65| style="text-align:right" | 85| 149.9236648(79)| 3.48(16) h| β⁺| ¹⁵⁰Gd| (2)−| |-id=Terbium-150m| style="text-indent:1em" | ^150mTb| colspan="3" style="text-indent:2em" | 461(27) keV| 5.8(2) min| β⁺| ¹⁵⁰Gd| 9+| |-id=Terbium-151| rowspan=2|¹⁵¹Tb| rowspan=2 style="text-align:right" | 65| rowspan=2 style="text-align:right" | 86| rowspan=2|150.9231090(44)| rowspan=2|17.609(1) h| β⁺ (99.99%)| ¹⁵¹Gd| rowspan=2|1/2+| rowspan=2||-| α (.0095%)| ¹⁴⁷Eu|-id=Terbium-151m| rowspan=2 style="text-indent:1em" | ^151mTb| rowspan=2 colspan="3" style="text-indent:2em" | 99.53(5) keV| rowspan=2|25(3) s| IT (93.4%)| ¹⁵¹Tb| rowspan=2|11/2−| rowspan=2||-| β⁺ (6.6%)| ¹⁵¹Gd|-id=Terbium-152| rowspan=3|¹⁵²Tb| rowspan=3 style="text-align:right" | 65| rowspan=3 style="text-align:right" | 87| rowspan=3|151.924082(43)| rowspan=3|17.8784(95) h^[3] | EC (83%)^[3] | rowspan=2|¹⁵²Gd| rowspan=3|2−| rowspan=3||-| β⁺ (17%)^[3] |-| α (<7×10^-7%)^[4] | ¹⁴⁸Eu|-id=Terbium-152m1| style="text-indent:1em" | ^152m1Tb| colspan="3" style="text-indent:2em" | 342.15(16) keV| 960(10) ns| IT| ¹⁵²Tb| 5−||-id=Terbium-152m2| rowspan=2 style="text-indent:1em" | ^152m2Tb| rowspan=2 colspan="3" style="text-indent:2em" | 501.74(19) keV| rowspan=2|4.2(1) min| IT (78.9%)| ¹⁵²Tb| rowspan=2|8+| rowspan=2||-| β⁺ (21.1%)| ¹⁵²Gd|-id=Terbium-153| ¹⁵³Tb| style="text-align:right" | 65| style="text-align:right" | 88| 152.9234417(42)| 2.34(1) d| β⁺| ¹⁵³Gd| 5/2+||-id=Terbium-153m| style="text-indent:1em" | ^153mTb| colspan="3" style="text-indent:2em" | 163.175(5) keV| 186(4) μs| IT| ¹⁵³Tb| 11/2−||-id=Terbium-154| ¹⁵⁴Tb| style="text-align:right" | 65| style="text-align:right" | 89| 153.924684(49)| 9.994(39) h| β⁺| ¹⁵⁴Gd| 3−||-id=Terbium-154m1| style="text-indent:1em" | ^154m1Tb^[1] | colspan="3" style="text-indent:2em" | 130(50)# keV| 21.5(4) h| β⁺| ¹⁵⁴Gd| 0−||-id=Terbium-154m2| style="text-indent:1em" | ^154m2Tb^[1] | colspan="3" style="text-indent:2em" | 200(150)# keV| 22.7(5) h| β⁺| ¹⁵⁴Gd| 7−||-id=Terbium-154m3| style="text-indent:1em" | ^154m3Tb| colspan="3" style="text-indent:2em" | 405(150)# keV| 513(42) ns| IT| ¹⁵⁴Tb|||-id=Terbium-155| ¹⁵⁵Tb| style="text-align:right" | 65| style="text-align:right" | 90| 154.923510(11)| 5.32(6) d| EC| ¹⁵⁵Gd| 3/2+||-id=Terbium-156| ¹⁵⁶Tb| style="text-align:right" | 65| style="text-align:right" | 91| 155.9247542(40)| 5.35(10) d| β⁺| ¹⁵⁶Gd| 3−| |-id=Terbium-156m1| style="text-indent:1em" | ^156m1Tb| colspan="3" style="text-indent:2em" | 88.4(2) keV| 5.3(2) h| IT| ¹⁵⁶Tb| (0+)||-id=Terbium-156m2| style="text-indent:1em" | ^156m2Tb| colspan="3" style="text-indent:2em" | 100(50)# keV| 24.4(10) h| IT| ¹⁵⁶Tb| (7−)||-id=Terbium-157| ¹⁵⁷Tb| style="text-align:right" | 65| style="text-align:right" | 92| 156.9240319(11)| 71(7) y| EC| ¹⁵⁷Gd| 3/2+||-id=Terbium-158| rowspan=2|¹⁵⁸Tb| rowspan=2 style="text-align:right" | 65| rowspan=2 style="text-align:right" | 93| rowspan=2|157.9254199(14)| rowspan=2|180(11) y| β⁺ (83.4%)| ¹⁵⁸Gd| rowspan=2|3−| rowspan=2||-| β⁻ (16.6%)| ¹⁵⁸Dy|-id=Terbium-158m1| style="text-indent:1em" | ^158m1Tb| colspan="3" style="text-indent:2em" | 110.3(12) keV| 10.70(17) s| IT| ¹⁵⁸Tb| 0−| |-id=Terbium-158m2| style="text-indent:1em" | ^158m2Tb| colspan="3" style="text-indent:2em" | 388.39(11) keV| 0.40(4) ms| IT| ¹⁵⁸Tb| 7−||-id=Terbium-159| ¹⁵⁹Tb^[5] | style="text-align:right" | 65| style="text-align:right" | 94| 158.9253537(12)| colspan=3 align=center|Stable| 3/2+| 1.0000|-id=Terbium-160| ¹⁶⁰Tb| style="text-align:right" | 65| style="text-align:right" | 95| 159.9271746(12)| 72.3(2) d| β⁻| ¹⁶⁰Dy| 3−||-id=Terbium-161| ¹⁶¹Tb| style="text-align:right" | 65| style="text-align:right" | 96| 160.9275768(13)| 6.948(5) d| β⁻| ¹⁶¹Dy| 3/2+||-id=Terbium-162| ¹⁶²Tb| style="text-align:right" | 65| style="text-align:right" | 97| 161.9292754(22)| 7.60(15) min| β⁻| ¹⁶²Dy| (1−)||-id=Terbium-162m| style="text-indent:1em" | ^162mTb| colspan="3" style="text-indent:2em" | 286(3) keV| 10# min| | | 4−#||-id=Terbium-163| ¹⁶³Tb| style="text-align:right" | 65| style="text-align:right" | 98| 162.9306536(44)| 19.5(3) min| β⁻| ¹⁶³Dy| 3/2+||-id=Terbium-164| ¹⁶⁴Tb| style="text-align:right" | 65| style="text-align:right" | 99| 163.9333276(20)| 3.0(1) min| β⁻| ¹⁶⁴Dy| (5+)||-id=Terbium-164m| style="text-indent:1em" | ^164mTb| colspan="3" style="text-indent:2em" | 145(12) keV| 2# min| | | 2+#||-id=Terbium-165| ¹⁶⁵Tb| style="text-align:right" | 65| style="text-align:right" | 100| 164.9349552(17)| 2.11(10) min| β⁻| ¹⁶⁵Dy| (3/2+)||-id=Terbium-165m| style="text-indent:1em" | ^165mTb| colspan="3" style="text-indent:2em" | 207(5) keV| 0.81(8) μs| IT| ¹⁶⁵Tb| (7/2−)||-id=Terbium-166| ¹⁶⁶Tb| style="text-align:right" | 65| style="text-align:right" | 101| 165.9379397(16)| 27.1(15) s| β⁻| ¹⁶⁶Dy| (1−)||-id=Terbium-166m| style="text-indent:1em" | ^166mTb| colspan="3" style="text-indent:2em" | 159.0(15) keV| 3.5(4) μs| IT| ¹⁶⁶Tb| 4−#||-id=Terbium-167| ¹⁶⁷Tb| style="text-align:right" | 65| style="text-align:right" | 102| 166.9400070(21)| 18.9(16) s| β⁻| ¹⁶⁷Dy| (3/2+)||-id=Terbium-167m| style="text-indent:1em" | ^167mTb| colspan="3" style="text-indent:2em" | 200(6) keV| 1.2(1) μs| IT| ¹⁶⁷Tb| (7/2−)||-id=Terbium-168| ¹⁶⁸Tb| style="text-align:right" | 65| style="text-align:right" | 103| 167.9433371(45)| 9.4(4) s| β⁻| ¹⁶⁸Dy| (4−)||-id=Terbium-168m| style="text-indent:1em" | ^168mTb| colspan="3" style="text-indent:2em" | 211(1) keV| 0.71(3) μs| IT| ¹⁶⁸Tb| (6+)||-id=Terbium-169| ¹⁶⁹Tb| style="text-align:right" | 65| style="text-align:right" | 104| 168.94581(32)#| 5.13(32) s| β⁻| ¹⁶⁹Dy| 3/2+#||-id=Terbium-170| ¹⁷⁰Tb| style="text-align:right" | 65| style="text-align:right" | 105| 169.94986(32)#| 960(78) ms| β⁻| ¹⁷⁰Dy| 2−#||-id=Terbium-171| ¹⁷¹Tb| style="text-align:right" | 65| style="text-align:right" | 106| 170.95301(43)#| 1.23(10) s| β⁻| ¹⁷¹Dy| 3/2+#||-id=Terbium-172| ¹⁷²Tb| style="text-align:right" | 65| style="text-align:right" | 107| 171.95739(54)#| 760(190) ms| β⁻| ¹⁷²Dy| 6+#||-id=Terbium-173| ¹⁷³Tb| style="text-align:right" | 65| style="text-align:right" | 108| 172.96081(54)#| 400# ms
[>550 ns]| | | 3/2+#||-id=Terbium-174| ¹⁷⁴Tb| style="text-align:right" | 65| style="text-align:right" | 109| 173.96568(54)#| 240# ms
[>550 ns]| | | 2−#|

References

Isotope masses from:
- - Isotopic compositions and standard atomic masses from:
    - - Half-life, spin, and isomer data selected from the following sources.

Notes and References

Order of ground state and isomer is uncertain.
Discovery of this isotope is disputed.
Collins . S.M. . Köster . U. . Robinson . A.P. . Ivanov . P. . Cocolios . T.E. . Russell . B. . Fenwick . A.J. . Bernerd . C. . Stegemann . S. . Johnston . K. . Gerami . A.M. . Chrysalidis . K. . Mohamud . H. . Ramirez . N. . Bhaisare . A. . Mewburn-Crook . J. . Cullen . D.M. . Pietras . B. . Pells . S. . Dockx . K. . Stucki . N. . Regan . P.H. . Determination of the Terbium-152 half-life from mass-separated samples from CERN-ISOLDE and assessment of the radionuclide purity . Applied Radiation and Isotopes . Elsevier BV . 202 . 2023 . 0969-8043 . 10.1016/j.apradiso.2023.111044 . 111044. 37797447 . free .
Web site: Adopted Levels for ¹⁵²Tb. NNDC Chart of Nuclides.
[Fission product]