Isotopes of terbium

Last updated
Isotopes of terbium  (65Tb)
Main isotopes [1] Decay
abun­dance half-life (t1/2) mode pro­duct
157Tb synth 71 y ε 157Gd
158Tbsynth180 yε 158Gd
β 158Dy
159Tb100% stable
Standard atomic weight Ar°(Tb)
  • 158.925354±0.000007
  • 158.93±0.01 (abridged) [2] [3]

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 (t1/2 = 24.4 hours), 154m2Tb (t1/2 = 22.7 hours) and 154m1Tb (t1/2 = 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

Nuclide
[n 1]
Z N Isotopic mass (Da)
[n 2] [n 3]
Half-life
[n 4]
Decay
mode

[n 5]
Daughter
isotope

[n 6] [n 7]
Spin and
parity
[n 8] [n 4]
Natural abundance (mole fraction)
Excitation energy [n 4] Normal proportionRange of variation
135Tb65700.94(+33−22) ms(7/2−)
136Tb6571135.96138(64)#0.2# s
137Tb6572136.95598(64)#600# ms11/2−#
138Tb6573137.95316(43)#800# ms [>200 ns] β+ 138Gd
p 137Gd
139Tb6574138.94829(32)#1.6(2) sβ+139Gd11/2−#
140Tb6575139.94581(86)2.4(2) sβ+ (99.74%)140Gd5
β+, p (.26%)139Eu
141Tb6576140.94145(11)3.5(2) sβ+141Gd(5/2−)
141mTb0(200)# keV7.9(6) sβ+141Gd11/2−#
142Tb6577141.93874(32)#597(17) msβ+ (96.8(4)%)142Gd1+
EC (3.2(4)%)
β+, p141Eu
142m1Tb280.2(10) keV303(17) ms IT (99.5%)142Tb(5−)
β+ (.5%)142Gd
142m2Tb621.4(11) keV15(4) µs
143Tb6578142.93512(6)12(1) sβ+143Gd(11/2−)
143mTb0(100)# keV<21 sβ+143Gd5/2+#
144Tb6579143.93305(3)~1 sβ+144Gd1+
β+, p (rare)143Eu
144m1Tb396.9(5) keV4.25(15) sIT (66%)144Tb(6−)
β+ (34%)144Gd
β+, p (<1%)143Eu
144m2Tb476.2(5) keV2.8(3) µs(8−)
144m3Tb517.1(5) keV670(60) ns(9+)
144m4Tb544.5(6) keV<300 ns(10+)
145Tb6580144.92927(6)20# minβ+145Gd(3/2+)
145mTb0(100)# keV30.9(7) sβ+145Gd(11/2−)
146Tb6581145.92725(5)8(4) sβ+146Gd1+
146m1Tb150(100)# keV24.1(5) sβ+146Gd5−
146m2Tb930(100)# keV1.18(2) ms(10+)
147Tb6582146.924045(13)1.64(3) hβ+147Gd1/2+#
147mTb50.6(9) keV1.87(5) minβ+147Gd(11/2)−
148Tb6583147.924272(15)60(1) minβ+148Gd2−
148m1Tb90.1(3) keV2.20(5) minβ+148Gd(9)+
148m2Tb8618.6(10) keV1.310(7) µs(27+)
149Tb6584148.923246(5)4.118(25) hβ+ (83.3%)149Gd1/2+
α (16.7%)145Eu
149mTb35.78(13) keV4.16(4) minβ+ (99.97%)149Gd11/2−
α (.022%)145Eu
150Tb6585149.923660(8)3.48(16) hβ+ (99.95%)150Gd(2−)
α (.05%)146Eu
150mTb457(29) keV5.8(2) minβ+150Gd9+
IT (rare)150Tb
151Tb6586150.923103(5)17.609(1) hβ+ (99.99%)151Gd1/2(+)
α (.0095%)147Eu
151mTb99.54(6) keV25(3) sIT (93.8%)151Tb(11/2−)
β+ (6.2%)151Gd
152Tb6587151.92407(4)17.8784(95) h [4] β+152Gd2−
α (7×10−7%)148Eu
152m1Tb342.15(16) keV0.96 µs5−
152m2Tb501.74(19) keV4.2(1) minIT (78.8%)152Tb8+
β+ (21.2%)152Gd
153Tb6588152.923435(5)2.34(1) dβ+153Gd5/2+
153mTb163.175(5) keV186(4) µs11/2−
154Tb6589153.92468(5)21.5(4) hβ+ (99.9%)154Gd0(+#)
β (.1%)154Dy
154m1Tb12(7) keV9.4(4) hβ+ (78.2%)154Gd3−
IT (21.8%)154Tb
β (.1%)154Dy
154m2Tb200(150)# keV22.7(5) h7−
154m3Tb0+Z keV513(42) ns
155Tb6590154.923505(13)5.32(6) dEC155Gd3/2+
156Tb6591155.924747(5)5.35(10) dβ+156Gd3−
β (rare)156Dy
156m1Tb54(3) keV24.4(10) hIT156Tb(7−)
156m2Tb88.4(2) keV5.3(2) h(0+)
157Tb6592156.9240246(27)71(7) yEC157Gd3/2+
158Tb6593157.9254131(28)180(11) yβ+ (83.4%)158Gd3−
β (16.6%)158Dy
158m1Tb110.3(12) keV10.70(17) sIT (99.39%)158Tb0−
β (.6%)158Dy
β+ (.01%)158Gd
158m2Tb388.37(15) keV0.40(4) ms7−
159Tb [n 9] 6594158.9253468(27)Stable3/2+1.0000
160Tb6595159.9271676(27)72.3(2) dβ160Dy3−
161Tb [n 9] 6596160.9275699(28)6.906(19) dβ161Dy3/2+
162Tb6597161.92949(4)7.60(15) minβ162Dy1−
163Tb6598162.930648(5)19.5(3) minβ163Dy3/2+
164Tb6599163.93335(11)3.0(1) minβ164Dy(5+)
165Tb65100164.93488(21)#2.11(10) minβ165mDy3/2+#
166Tb65101165.93799(11)25.6(22) sβ166Dy
167Tb65102166.94005(43)#19.4(27) sβ167Dy3/2+#
168Tb65103167.94364(54)#8.2(13) sβ168Dy4−#
169Tb65104168.94622(64)#5.13(32) sβ169Dy3/2+#
170Tb65105169.95025(75)#960(78) msβ170Dy
171Tb65106170.95330(86)#1.23(10) sβ171Dy3/2+#
172Tb65107760(190) msβ172Dy6+#
This table header & footer:
  1. mTb  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. 1 2 3 #  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 italics symbol as daughter  Daughter product is nearly stable.
  7. Bold symbol as daughter  Daughter product is stable.
  8. () spin value  Indicates spin with weak assignment arguments.
  9. 1 2 Fission product

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References

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