Isotopes of dysprosium – Wikipedia

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Nuclides with atomic number of 66 but with different mass numbers

Naturally occurring dysprosium (66Dy) is composed of 7 stable isotopes, 156Dy, 158Dy, 160Dy, 161Dy, 162Dy, 163Dy and 164Dy, with 164Dy being the most abundant (28.18% natural abundance). Twenty-nine radioisotopes have been characterized, with the most stable being 154Dy with a half-life of 3.0 million years, 159Dy with a half-life of 144.4 days, and 166Dy with a half-life of 81.6 hours. All of the remaining radioactive isotopes have half-lives that are less than 10 hours, and the majority of these have half-lives that are less than 30 seconds. This element also has 12 meta states, with the most stable being 165mDy (half-life 1.257 minutes), 147mDy (half-life 55.7 seconds) and 145mDy (half-life 13.6 seconds).

The primary decay mode before the most abundant stable isotope, 164Dy, is electron capture, and the primary mode after is beta decay. The primary decay products before 164Dy are terbium isotopes, and the primary products after are holmium isotopes. Dysprosium is the heaviest element to have isotopes that are predicted to be stable rather than observationally stable isotopes that are predicted to be radioactive.

List of isotopes[edit]

Nuclide
[n 1]		 Z N Isotopic mass (Da)
[n 2][n 3]		 Half-life
[n 4]		 Decay
mode
[n 5]		 Daughter
isotope
[n 6]		 Spin and
parity
[n 7][n 4]		 Natural abundance (mole fraction)
Excitation energy Normal proportion Range of variation
138Dy 66 72 137.96249(64)# 200# ms 0+
139Dy 66 73 138.95954(54)# 600(200) ms 7/2+#
140Dy 66 74 139.95401(54)# 700# ms β+ 140Tb 0+
140mDy 2166.1(5) keV 7.0(5) μs (8−)
141Dy 66 75 140.95135(32)# 0.9(2) s β+ 141Tb (9/2−)
β+, p (rare) 140Gd
142Dy 66 76 141.94637(39)# 2.3(3) s β+ (99.94%) 142Tb 0+
β+, p (.06%) 141Gd
143Dy 66 77 142.94383(21)# 5.6(10) s β+ 143Tb (1/2+)
β+, p (rare) 142Gd
143mDy 310.7(6) keV 3.0(3) s (11/2−)
144Dy 66 78 143.93925(3) 9.1(4) s β+ 144Tb 0+
β+, p (rare) 143Gd
145Dy 66 79 144.93743(5) 9.5(10) s β+ 145Tb (1/2+)
β+, p (rare) 144Gd
145mDy 118.2(2) keV 14.1(7) s β+ 145Tb (11/2−)
146Dy 66 80 145.932845(29) 33.2(7) s β+ 146Tb 0+
146mDy 2935.7(6) keV 150(20) ms IT 146Dy (10+)#
147Dy 66 81 146.931092(21) 40(10) s β+ (99.95%) 147Tb 1/2+
β+, p (.05%) 146Tb
147m1Dy 750.5(4) keV 55(1) s β+ (65%) 147Tb 11/2−
IT (35%) 147Dy
147m2Dy 3407.2(8) keV 0.40(1) μs (27/2−)
148Dy 66 82 147.927150(11) 3.3(2) min β+ 148Tb 0+
149Dy 66 83 148.927305(9) 4.20(14) min β+ 149Tb 7/2(−)
149mDy 2661.1(4) keV 490(15) ms IT (99.3%) 149Dy (27/2−)
β+ (.7%) 149Tb
150Dy 66 84 149.925585(5) 7.17(5) min β+ (64%) 150Tb 0+
α (36%) 146Gd
151Dy 66 85 150.926185(4) 17.9(3) min β+ (94.4%) 151Tb 7/2(−)
α (5.6%) 147Gd
152Dy 66 86 151.924718(6) 2.38(2) h EC (99.9%) 152Tb 0+
α (.1%) 148Gd
153Dy 66 87 152.925765(5) 6.4(1) h β+ (99.99%) 153Tb 7/2(−)
α (.00939%) 149Gd
154Dy 66 88 153.924424(8) 3.0(15)×106 y α 150Gd 0+
β+β+ (rare) 154Gd
155Dy 66 89 154.925754(13) 9.9(2) h β+ 155Tb 3/2−
155mDy 234.33(3) keV 6(1) μs 11/2−
156Dy 66 90 155.924283(7) Observationally Stable[n 8] 0+ 5.6(3)×10−4
157Dy 66 91 156.925466(7) 8.14(4) h β+ 157Tb 3/2−
157m1Dy 161.99(3) keV 1.3(2) μs 9/2+
157m2Dy 199.38(7) keV 21.6(16) ms IT 157Dy 11/2−
158Dy 66 92 157.924409(4) Observationally Stable[n 9] 0+ 9.5(3)×10−4
159Dy 66 93 158.9257392(29) 144.4(2) d EC 159Tb 3/2−
159mDy 352.77(14) keV 122(3) μs 11/2−
160Dy 66 94 159.9251975(27) Observationally Stable[n 10] 0+ 0.02329(18)
161Dy 66 95 160.9269334(27) Observationally Stable[n 11] 5/2+ 0.18889(42)
162Dy 66 96 161.9267984(27) Observationally Stable[n 12] 0+ 0.25475(36)
163Dy 66 97 162.9287312(27) Stable[n 13][n 14][4] 5/2− 0.24896(42)
164Dy 66 98 163.9291748(27) Stable[n 13] 0+ 0.28260(54)
165Dy 66 99 164.9317033(27) 2.334(1) h β− 165Ho 7/2+
165mDy 108.160(3) keV 1.257(6) min IT (97.76%) 165Dy 1/2−
β− (2.24%) 165Ho
166Dy 66 100 165.9328067(28) 81.6(1) h β− 166Ho 0+
167Dy 66 101 166.93566(6) 6.20(8) min β− 167Ho (1/2−)
168Dy 66 102 167.93713(15) 8.7(3) min β− 168Ho 0+
169Dy 66 103 168.94031(32) 39(8) s β− 169Ho (5/2−)
170Dy 66 104 169.94239(21)# 30# s β− 170Ho 0+
171Dy 66 105 170.94620(32)# 6# s β− 171Ho 7/2−#
172Dy 66 106 171.94876(43)# 3# s β− 172Ho 0+
173Dy 66 107 172.95300(54)# 2# s β− 173Ho 9/2+#
This table header & footer:
  1. ^ mDy – 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. ^ a b # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  5. ^
    Modes of decay:
  6. ^ Bold symbol as daughter – Daughter product is stable.
  7. ^ ( ) spin value – Indicates spin with weak assignment arguments.
  8. ^ Believed to undergo α decay to 152Gd or β+β+ decay to 156Gd with a half-life over 1018 years
  9. ^ Believed to undergo α decay to 154Gd or β+β+ decay to 158Gd
  10. ^ Believed to undergo α decay to 156Gd
  11. ^ Believed to undergo α decay to 157Gd
  12. ^ Believed to undergo α decay to 158Gd
  13. ^ a b Theoretically capable of spontaneous fission
  14. ^ Can undergo bound-state β− decay to 163Ho with a half-life of 47 days when fully ionized
  • Geologically exceptional samples are found associated with the Oklo natural nuclear fission reactor, in which the isotopic composition lies outside the reported range. The uncertainty in the atomic mass may exceed the stated value for such specimens.

Dysprosium-165[edit]

The radioactive isotope 165Dy, with a half life of 2.334 hours, has radiopharmaceutical uses.

References[edit]