Isotopes of terbium

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Naturally occurring terbium (Tb) is composed of 1 stable isotope, 159Tb. 36 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 minus decay. The primary decay products before 159Tb are element Gd (gadolinium) isotopes, and the primary products behind are element Dy (dysprosium) isotopes.

Standard atomic mass: 158.92535(2) u

Table[edit]

nuclide
symbol
Z(p) N(n)  
isotopic mass (u)
 
half-life decay
mode(s)[1][n 1]
daughter
isotope(s)[n 2]
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] β+ 138Gd
p 137Gd
139Tb 65 74 138.94829(32)# 1.6(2) s β+ 139Gd 11/2-#
140Tb 65 75 139.94581(86) 2.4(2) s β+ (99.74%) 140Gd 5
β+, p (.26%) 139Eu
141Tb 65 76 140.94145(11) 3.5(2) s β+ 141Gd (5/2-)
141mTb 0(200)# keV 7.9(6) s β+ 141Gd 11/2-#
142Tb 65 77 141.93874(32)# 597(17) ms β+ 142Gd 1+
β+, p 141Eu
142m1Tb 280.2(10) keV 303(17) ms IT (99.5%) 142Tb (5-)
β+ (.5%) 142Gd
142m2Tb 621.4(11) keV 15(4) µs
143Tb 65 78 142.93512(6) 12(1) s β+ 143Gd (11/2-)
143mTb 0(100)# keV <21 s β+ 143Gd 5/2+#
144Tb 65 79 143.93305(3) ~1 s β+ 144Gd 1+
β+, p (rare) 143Eu
144m1Tb 396.9(5) keV 4.25(15) s IT (66%) 144Tb (6-)
β+ (34%) 144Gd
β+, p (<1%) 143Eu
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 β+ 145Gd (3/2+)
145mTb 0(100)# keV 30.9(7) s β+ 145Gd (11/2-)
146Tb 65 81 145.92725(5) 8(4) s β+ 146Gd 1+
146m1Tb 150(100)# keV 24.1(5) s β+ 146Gd 5-
146m2Tb 930(100)# keV 1.18(2) ms (10+)
147Tb 65 82 146.924045(13) 1.64(3) h β+ 147Gd 1/2+#
147mTb 50.6(9) keV 1.87(5) min β+ 147Gd (11/2)-
148Tb 65 83 147.924272(15) 60(1) min β+ 148Gd 2-
148m1Tb 90.1(3) keV 2.20(5) min β+ 148Gd (9)+
148m2Tb 8618.6(10) keV 1.310(7) µs (27+)
149Tb 65 84 148.923246(5) 4.118(25) h β+ (83.3%) 149Gd 1/2+
α (16.7%) 145Eu
149mTb 35.78(13) keV 4.16(4) min β+ (99.97%) 149Gd 11/2-
α (.022%) 145Eu
150Tb 65 85 149.923660(8) 3.48(16) h β+ (99.95%) 150Gd (2-)
α (.05%) 146Eu
150mTb 457(29) keV 5.8(2) min β+ 150Gd 9+
IT (rare) 150Tb
151Tb 65 86 150.923103(5) 17.609(1) h β+ (99.99%) 151Gd 1/2(+)
α (.0095%) 147Eu
151mTb 99.54(6) keV 25(3) s IT (93.8%) 151Tb (11/2-)
β+ (6.2%) 151Gd
152Tb 65 87 151.92407(4) 17.5(1) h β+ 152Gd 2-
α (7×10−7%) 148Eu
152m1Tb 342.15(16) keV 0.96 µs 5-
152m2Tb 501.74(19) keV 4.2(1) min IT (78.8%) 152Tb 8+
β+ (21.2%) 152Gd
153Tb 65 88 152.923435(5) 2.34(1) d β+ 153Gd 5/2+
153mTb 163.175(5) keV 186(4) µs 11/2-
154Tb 65 89 153.92468(5) 21.5(4) h β+ (99.9%) 154Gd 0(+#)
β- (.1%) 154Dy
154m1Tb 12(7) keV 9.4(4) h β+ (78.2%) 154Gd 3-
IT (21.8%) 154Tb
β- (.1%) 154Dy
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 EC 155Gd 3/2+
156Tb 65 91 155.924747(5) 5.35(10) d β+ 156Gd 3-
β- (rare) 156Dy
156m1Tb 54(3) keV 24.4(10) h IT 156Tb (7-)
156m2Tb 88.4(2) keV 5.3(2) h (0+)
157Tb 65 92 156.9240246(27) 71(7) a EC 157Gd 3/2+
158Tb 65 93 157.9254131(28) 180(11) a β+ (83.4%) 158Gd 3-
β- (16.6%) 158Dy
158m1Tb 110.3(12) keV 10.70(17) s IT (99.39%) 158Tb 0-
β- (.6%) 158Dy
β+ (.01%) 158Gd
158m2Tb 388.37(15) keV 0.40(4) ms 7-
159Tb[n 3] 65 94 158.9253468(27) Stable[n 4] 3/2+ 1.0000
160Tb 65 95 159.9271676(27) 72.3(2) d β- 160Dy 3-
161Tb[n 3] 65 96 160.9275699(28) 6.906(19) d β- 161Dy 3/2+
162Tb 65 97 161.92949(4) 7.60(15) min β- 162Dy 1-
163Tb 65 98 162.930648(5) 19.5(3) min β- 163Dy 3/2+
164Tb 65 99 163.93335(11) 3.0(1) min β- 164Dy (5+)
165Tb 65 100 164.93488(21)# 2.11(10) min β- 165mDy 3/2+#
166Tb 65 101 165.93799(11) 25.6(22) s β- 166Dy
167Tb 65 102 166.94005(43)# 19.4(27) s β- 167Dy 3/2+#
168Tb 65 103 167.94364(54)# 8.2(13) s β- 168Dy 4-#
169Tb 65 104 168.94622(64)# 2# s β- 169Dy 3/2+#
170Tb 65 105 169.95025(75)# 3# s β- 170Dy
171Tb 65 106 170.95330(86)# 500# ms β- 171Dy 3/2+#
  1. ^ Abbreviations:
    EC: Electron capture
    IT: Isomeric transition
  2. ^ Bold for stable isotopes
  3. ^ a b Fission product
  4. ^ Theoretically capable of spontaneous fission

Notes[edit]

  • 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[edit]

  1. ^ http://www.nucleonica.net/unc.aspx


Isotopes of gadolinium Isotopes of terbium Isotopes of dysprosium
Table of nuclides