Naturally occurring terbium (Tb) is composed of 1 stable isotope, 159-Tb. 33 radioisotopes have been characterized, with the most stable being 158-Tb with a half-life of 180 years, 157-Tb with a half-life of 71 years, and 160-Tb with a half-life of 72.3 days. All of the remaining radioactive isotopes have half-lifes that are less than 6.907 days, and the majority of these have half lifes that are less than 24 seconds. This element also has 18 meta states, with the most stable being 156m1-Tb (t½ 24.4 hours), 154m2-Tb (t½ 22.7 hours) and 154m1-Tb (t½ 9.4 hours).
Additional recommended knowledge
The primary decay mode before the most abundant stable isotope, 159-Tb, is electron capture, and the primary mode behind is beta minus decay. The primary decay products before 159-Tb are element Gd (gadolinium) isotopes, and the primary products behind are element Dy (dysprosium) isotopes.
Standard atomic mass: 158.92535(2) u
Table
nuclide
symbol
| Z(p)
| N(n)
|
isotopic mass (u)
| half-life
| nuclear
spin
| representative
isotopic
composition
(mole fraction)
| range of natural
variation
(mole fraction)
|
| excitation energy
|
| 135Tb
| 65
| 70
|
| 0.94(+33-22) ms
| (7/2-)
|
|
|
| 136Tb
| 65
| 71
| 135.96138(64)#
| 0.2# s
|
|
|
|
| 137Tb
| 65
| 72
| 136.95598(64)#
| 600# ms
| 11/2-#
|
|
|
| 138Tb
| 65
| 73
| 137.95316(43)#
| 800# ms [>200 ns]
|
|
|
|
| 139Tb
| 65
| 74
| 138.94829(32)#
| 1.6(2) s
| 11/2-#
|
|
|
| 140Tb
| 65
| 75
| 139.94581(86)
| 2.4(2) s
| 5
|
|
|
| 141Tb
| 65
| 76
| 140.94145(11)
| 3.5(2) s
| (5/2-)
|
|
|
| 141mTb
| 0(200)# keV
| 7.9(6) s
| 11/2-#
|
|
|
| 142Tb
| 65
| 77
| 141.93874(32)#
| 597(17) ms
| 1+
|
|
|
| 142m1Tb
| 280.2(10) keV
| 303(17) ms
| (5-)
|
|
|
| 142m2Tb
| 621.4(11) keV
| 15(4) µs
|
|
|
|
| 143Tb
| 65
| 78
| 142.93512(6)
| 12(1) s
| (11/2-)
|
|
|
| 143mTb
| 0(100)# keV
| <21 s
| 5/2+#
|
|
|
| 144Tb
| 65
| 79
| 143.93305(3)
| ~1 s
| 1+
|
|
|
| 144m1Tb
| 396.9(5) keV
| 4.25(15) s
| (6-)
|
|
|
| 144m2Tb
| 476.2(5) keV
| 2.8(3) µs
| (8-)
|
|
|
| 144m3Tb
| 517.1(5) keV
| 670(60) ns
| (9+)
|
|
|
| 144m4Tb
| 544.5(6) keV
| <300 ns
| (10+)
|
|
|
| 145Tb
| 65
| 80
| 144.92927(6)
| 20# min
| (3/2+)
|
|
|
| 145mTb
| 0(100)# keV
| 30.9(7) s
| (11/2-)
|
|
|
| 146Tb
| 65
| 81
| 145.92725(5)
| 8(4) s
| 1+
|
|
|
| 146m1Tb
| 150(100)# keV
| 24.1(5) s
| 5-
|
|
|
| 146m2Tb
| 930(100)# keV
| 1.18(2) ms
| (10+)
|
|
|
| 147Tb
| 65
| 82
| 146.924045(13)
| 1.64(3) h
| 1/2+#
|
|
|
| 147mTb
| 50.6(9) keV
| 1.87(5) min
| (11/2)-
|
|
|
| 148Tb
| 65
| 83
| 147.924272(15)
| 60(1) min
| 2-
|
|
|
| 148m1Tb
| 90.1(3) keV
| 2.20(5) min
| (9)+
|
|
|
| 148m2Tb
| 8618.6(10) keV
| 1.310(7) µs
| (27+)
|
|
|
| 149Tb
| 65
| 84
| 148.923246(5)
| 4.118(25) h
| 1/2+
|
|
|
| 149mTb
| 35.78(13) keV
| 4.16(4) min
| 11/2-
|
|
|
| 150Tb
| 65
| 85
| 149.923660(8)
| 3.48(16) h
| (2-)
|
|
|
| 150mTb
| 457(29) keV
| 5.8(2) min
| 9+
|
|
|
| 151Tb
| 65
| 86
| 150.923103(5)
| 17.609(1) h
| 1/2(+)
|
|
|
| 151mTb
| 99.54(6) keV
| 25(3) s
| (11/2-)
|
|
|
| 152Tb
| 65
| 87
| 151.92407(4)
| 17.5(1) h
| 2-
|
|
|
| 152m1Tb
| 342.15(16) keV
| 0.96 µs
| 5-
|
|
|
| 152m2Tb
| 501.74(19) keV
| 4.2(1) min
| 8+
|
|
|
| 153Tb
| 65
| 88
| 152.923435(5)
| 2.34(1) d
| 5/2+
|
|
|
| 153mTb
| 163.175(5) keV
| 186(4) µs
| 11/2-
|
|
|
| 154Tb
| 65
| 89
| 153.92468(5)
| 21.5(4) h
| 0(+#)
|
|
|
| 154m1Tb
| 12(7) keV
| 9.4(4) h
| 3-
|
|
|
| 154m2Tb
| 200(150)# keV
| 22.7(5) h
| 7-
|
|
|
| 154m3Tb
| 0+Z keV
| 513(42) ns
|
|
|
|
| 155Tb
| 65
| 90
| 154.923505(13)
| 5.32(6) d
| 3/2+
|
|
|
| 156Tb
| 65
| 91
| 155.924747(5)
| 5.35(10) d
| 3-
|
|
|
| 156m1Tb
| 54(3) keV
| 24.4(10) h
| (7-)
|
|
|
| 156m2Tb
| 88.4(2) keV
| 5.3(2) h
| (0+)
|
|
|
| 157Tb
| 65
| 92
| 156.9240246(27)
| 71(7) a
| 3/2+
|
|
|
| 158Tb
| 65
| 93
| 157.9254131(28)
| 180(11) a
| 3-
|
|
|
| 158m1Tb
| 110.3(12) keV
| 10.70(17) s
| 0-
|
|
|
| 158m2Tb
| 388.37(15) keV
| 0.40(4) ms
| 7-
|
|
|
| 159Tb
| 65
| 94
| 158.9253468(27)
| STABLE
| 3/2+
| 1.0000
|
|
| 160Tb
| 65
| 95
| 159.9271676(27)
| 72.3(2) d
| 3-
|
|
|
| 161Tb
| 65
| 96
| 160.9275699(28)
| 6.906(19) d
| 3/2+
|
|
|
| 162Tb
| 65
| 97
| 161.92949(4)
| 7.60(15) min
| 1-
|
|
|
| 163Tb
| 65
| 98
| 162.930648(5)
| 19.5(3) min
| 3/2+
|
|
|
| 164Tb
| 65
| 99
| 163.93335(11)
| 3.0(1) min
| (5+)
|
|
|
| 165Tb
| 65
| 100
| 164.93488(21)#
| 2.11(10) min
| 3/2+#
|
|
|
| 166Tb
| 65
| 101
| 165.93799(11)
| 25.6(22) s
|
|
|
|
| 167Tb
| 65
| 102
| 166.94005(43)#
| 19.4(27) s
| 3/2+#
|
|
|
| 168Tb
| 65
| 103
| 167.94364(54)#
| 8.2(13) s
| 4-#
|
|
|
| 169Tb
| 65
| 104
| 168.94622(64)#
| 2# s
| 3/2+#
|
|
|
| 170Tb
| 65
| 105
| 169.95025(75)#
| 3# s
|
|
|
|
| 171Tb
| 65
| 106
| 170.95330(86)#
| 500# ms
| 3/2+#
|
|
|
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
- Isotope masses from Ame2003 Atomic Mass Evaluation by G. Audi, A.H. Wapstra, C. Thibault, J. Blachot and O. Bersillon in Nuclear Physics A729 (2003).
- Isotopic compositions and standard atomic masses from Atomic weights of the elements. Review 2000 (IUPAC Technical Report). Pure Appl. Chem. Vol. 75, No. 6, pp. 683-800, (2003) and Atomic Weights Revised (2005).
- Half-life, spin, and isomer data selected from these sources. Editing notes on this article's talk page.
- Audi, Bersillon, Blachot, Wapstra. The Nubase2003 evaluation of nuclear and decay properties, Nuc. Phys. A 729, pp. 3-128 (2003).
- National Nuclear Data Center, Brookhaven National Laboratory. Information extracted from the NuDat 2.1 database (retrieved Sept. 2005).
- David R. Lide (ed.), Norman E. Holden in CRC Handbook of Chemistry and Physics, 85th Edition, online version. CRC Press. Boca Raton, Florida (2005). Section 11, Table of the Isotopes.
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