# Isotopes of neodymium

Naturally occurring neodymium ($_{60}$Nd) is composed of five stable isotopes, $^{142}$Nd, $^{143}$Nd, $^{145}$Nd, $^{146}$Nd and $^{148}$Nd, with $^{142}$Nd being the most abundant (27.2% natural abundance), and two long-lived radioisotopes, $^{144}$Nd and $^{150}$Nd. In all, 35 radioisotopes of neodymium have been characterized up to now, with the most stable being naturally occurring isotopes $^{144}$Nd (alpha decay, a half-life (t$_{1/2}$) of 2.29×10$^{15}$ years) and $^{150}$Nd (double beta decay, t$_{1/2}$ of 9.3×10$^{18}$ years), and for practical purposes they can be considered to be stable as well. All of the remaining radioactive isotopes have half-lives that are less than 11 days, and the majority of these have half-lives that are less than 70 seconds; the most stable artificial isotope is $^{147}$Nd with a half-life of 10.98 days. This element also has 15 known meta states with the most stable being $^{139m}$Nd (t$_{1/2}$ 5.5 hours), $^{135m}$Nd (t$_{1/2}$ 5.5 minutes) and $^{133m1}$Nd (t$_{1/2}$ ~70 seconds).
The primary decay modes for isotopes lighter than the most abundant stable isotope (also the only theoretically stable isotope), $^{142}$Nd, are electron capture and positron decay, and the primary mode for heavier radioisotopes is beta decay. The primary decay products for lighter radioisotopes are praseodymium isotopes and the primary products for heavier ones are promethium isotopes.

## Neodymium isotopes as fission products

Neodymium is one of the more common fission products that results from the splitting of uranium-233, uranium-235, plutonium-239 and plutonium-241. The distribution of resulting neodymium isotopes is distinctly different than those found in crustal rock formation on Earth. One of the methods used to verify that the Oklo Fossil Reactors in Gabon had produced a natural nuclear fission reactor some two billion years before present was to compare the relative abundances of neodymium isotopes found at the reactor site with those found elsewhere on Earth.

## List of isotopes

| Nuclide | Z | N | Isotopic mass (Da) | Half-life | Decay mode | Daughter isotope | Spin and parity | Natural abundance (mole fraction) | Natural abundance (mole fraction) |
| Nuclide | Excitation energy | Excitation energy | Excitation energy | Half-life | Decay mode | Daughter isotope | Spin and parity | Normal proportion | Range of variation |
| $^{125}$Nd | 60 | 65 | 124.94840(43)# | 0.65(15) s | β$^+$ | $^{125}$Pr | (5/2)(+#) | | |
| $^{125}$Nd | 60 | 65 | 124.94840(43)# | 0.65(15) s | β$^+$, p (?%) | $^{124}$Ce | (5/2)(+#) | | |
| $^{126}$Nd | 60 | 66 | 125.94269(32)# | 1# s [>200 ns] | | | 0+ | | |
| $^{127}$Nd | 60 | 67 | 126.93998(32)# | 1.8(4) s | β$^+$ | $^{127}$Pr | 5/2+# | | |
| $^{127}$Nd | 60 | 67 | 126.93998(32)# | 1.8(4) s | β$^+$, p (?%) | $^{126}$Ce | 5/2+# | | |
| $^{128}$Nd | 60 | 68 | 127.93502(22)# | 5# s | | | 0+ | | |
| $^{129}$Nd | 60 | 69 | 128.93304(22)# | 6.8(6) s | β$^+$ | $^{129}$Pr | 7/2− | | |
| $^{129}$Nd | 60 | 69 | 128.93304(22)# | 6.8(6) s | β$^+$, p (?%) | $^{128}$Ce | 7/2− | | |
| $^{129m1}$Nd | 17 keV | 17 keV | 17 keV | 2.6(4) s | β$^+$ | $^{129}$Pr | 1/2+ | | |
| $^{129m1}$Nd | 17 keV | 17 keV | 17 keV | 2.6(4) s | β$^+$, p (?%) | $^{128}$Ce | 1/2+ | | |
| $^{129m2}$Nd | 39 keV | 39 keV | 39 keV | 2.6(4) s | β$^+$ | $^{129}$Pr | 3/2+ | | |
| $^{129m2}$Nd | 39 keV | 39 keV | 39 keV | 2.6(4) s | β$^+$, p (?%) | $^{128}$Ce | 3/2+ | | |
| $^{129m3}$Nd | 108 keV | 108 keV | 108 keV | | IT (?%) | $^{129m2}$Nd | 5/2+ | | |
| $^{129m3}$Nd | 108 keV | 108 keV | 108 keV | | IT (?%) | $^{129}$Nd | 5/2+ | | |
| $^{129m4}$Nd | 1893 keV | 1893 keV | 1893 keV | | IT | $^{129}$Nd | (17/2+) | | |
| $^{129m5}$Nd | 2109 keV | 2109 keV | 2109 keV | | IT | $^{129}$Nd | (19/2+) | | |
| $^{129m6}$Nd | 2284 keV | 2284 keV | 2284 keV | 0.48(4) μs | IT | $^{129}$Nd | (21/2+) | | |
| $^{130}$Nd | 60 | 70 | 129.928506(30) | 21(3) s | β$^+$ | $^{130}$Pr | 0+ | | |
| $^{131}$Nd | 60 | 71 | 130.927248(30) | 25.4(9) s | β$^+$ | $^{131}$Pr | (5/2+) | | |
| $^{131}$Nd | 60 | 71 | 130.927248(30) | 25.4(9) s | β$^+$, p (?%) | $^{130}$Ce | (5/2+) | | |
| $^{132}$Nd | 60 | 72 | 131.923321(26) | 1.56(10) min | β$^+$ | $^{132}$Pr | 0+ | | |
| $^{133}$Nd | 60 | 73 | 132.922348(50) | 70(10) s | β$^+$ | $^{133}$Pr | (7/2+) | | |
| $^{133m1}$Nd | 127.97(12) keV | 127.97(12) keV | 127.97(12) keV | ~70 s | β$^+$ (?%) | $^{133}$Pr | (1/2)+ | | |
| $^{133m1}$Nd | 127.97(12) keV | 127.97(12) keV | 127.97(12) keV | ~70 s | IT (?%) | $^{133}$Nd | (1/2)+ | | |
| $^{133m2}$Nd | 176.10(10) keV | 176.10(10) keV | 176.10(10) keV | 301(18) ns | IT | $^{133}$Nd | (9/2–) | | |
| $^{134}$Nd | 60 | 74 | 133.918790(13) | 8.5(15) min | β$^+$ | $^{134}$Pr | 0+ | | |
| $^{134m}$Nd | 2293.0(4) keV | 2293.0(4) keV | 2293.0(4) keV | 389(17) μs | IT | $^{134}$Nd | 8– | | |
| $^{135}$Nd | 60 | 75 | 134.918181(21) | 12.4(6) min | β$^+$ | $^{135}$Pr | 9/2– | | |
| $^{135m}$Nd | 64.95(24) keV | 64.95(24) keV | 64.95(24) keV | 5.5(5) min | β$^+$ | $^{135}$Pr | (1/2+) | | |
| $^{136}$Nd | 60 | 76 | 135.914976(13) | 50.65(33) min | β$^+$ | $^{136}$Pr | 0+ | | |
| $^{137}$Nd | 60 | 77 | 136.914563(13) | 38.5(15) min | β$^+$ | $^{137}$Pr | 1/2+ | | |
| $^{137m}$Nd | 519.43(20) keV | 519.43(20) keV | 519.43(20) keV | 1.60(15) s | IT | $^{137}$Nd | 11/2– | | |
| $^{138}$Nd | 60 | 78 | 137.911951(12) | 5.04(9) h | β$^+$ | $^{138}$Pr | 0+ | | |
| $^{138m}$Nd | 3174.5(4) keV | 3174.5(4) keV | 3174.5(4) keV | 370(5) ns | IT | $^{138}$Nd | 10+ | | |
| $^{139}$Nd | 60 | 79 | 138.911951(30) | 29.7(5) min | β$^+$ | $^{139}$Pr | 3/2+ | | |
| $^{139m1}$Nd | 231.16(5) keV | 231.16(5) keV | 231.16(5) keV | 5.50(20) h | β$^+$ (87.0%) | $^{139}$Pr | 11/2– | | |
| $^{139m1}$Nd | 231.16(5) keV | 231.16(5) keV | 231.16(5) keV | 5.50(20) h | IT (13.0%) | $^{139}$Nd | 11/2– | | |
| $^{139m2}$Nd | 2616.9(6) keV | 2616.9(6) keV | 2616.9(6) keV | 276.8(18) ns | IT | $^{139}$Nd | 23/2 | | |
| $^{140}$Nd | 60 | 80 | 139.9095461(35) | 3.37(2) d | EC | $^{140}$Pr | 0+ | | |
| $^{140m1}$Nd | 2221.65(9) keV | 2221.65(9) keV | 2221.65(9) keV | 600(50) μs | IT | $^{140}$Nd | 7– | | |
| $^{140m2}$Nd | 7435.1(4) keV | 7435.1(4) keV | 7435.1(4) keV | 1.22(6) μs | IT | $^{140}$Nd | 20+ | | |
| $^{141}$Nd | 60 | 81 | 140.9096167(34) | 2.49(3) h | EC (97.28%) | $^{141}$Pr | 3/2+ | | |
| $^{141}$Nd | 60 | 81 | 140.9096167(34) | 2.49(3) h | β$^+$ (2.72%) | $^{141}$Pr | 3/2+ | | |
| $^{141m}$Nd | 756.51(5) keV | 756.51(5) keV | 756.51(5) keV | 62.0(8) s | IT (99.97%) | $^{141}$Nd | 11/2– | | |
| $^{141m}$Nd | 756.51(5) keV | 756.51(5) keV | 756.51(5) keV | 62.0(8) s | β$^+$ (0.032%) | $^{141}$Pr | 11/2– | | |
| $^{142}$Nd | 60 | 82 | 141.9077288(13) | Stable | Stable | Stable | 0+ | 0.27153(40) | |
| $^{143}$Nd | 60 | 83 | 142.9098198(13) | Observationally Stable | Observationally Stable | Observationally Stable | 7/2− | 0.12173(26) | |
| $^{144}$Nd | 60 | 84 | 143.9100928(13) | 2.29(16)×10$^{15}$ y | α | $^{140}$Ce | 0+ | 0.23798(19) | |
| $^{145}$Nd | 60 | 85 | 144.9125792(14) | Observationally Stable | Observationally Stable | Observationally Stable | 7/2− | 0.08293(12) | |
| $^{146}$Nd | 60 | 86 | 145.9131225(14) | Observationally Stable | Observationally Stable | Observationally Stable | 0+ | 0.17189(32) | |
| $^{147}$Nd | 60 | 87 | 146.9161060(14) | 10.98(1) d | β$^−$ | $^{147}$Pm | 5/2− | | |
| $^{148}$Nd | 60 | 88 | 147.9168990(22) | Observationally Stable | Observationally Stable | Observationally Stable | 0+ | 0.05756(21) | |
| $^{149}$Nd | 60 | 89 | 148.9201546(22) | 1.728(1) h | β$^−$ | $^{149}$Pm | 5/2− | | |
| $^{150}$Nd | 60 | 90 | 149.9209013(12) | 9.3(7)×10$^{18}$ y | β$^−$β$^−$ | $^{150}$Sm | 0+ | 0.05638(28) | |
| $^{151}$Nd | 60 | 91 | 150.9238394(12) | 12.44(7) min | β$^−$ | $^{151}$Pm | 3/2+ | | |
| $^{152}$Nd | 60 | 92 | 151.924691(26) | 11.4(2) min | β$^−$ | $^{152}$Pm | 0+ | | |
| $^{153}$Nd | 60 | 93 | 152.9277179(29) | 31.6(10) s | β$^−$ | $^{153}$Pm | (3/2)− | | |
| $^{153m}$Nd | 191.71(16) keV | 191.71(16) keV | 191.71(16) keV | 1.10(4) μs | IT | $^{153}$Nd | (5/2)+ | | |
| $^{154}$Nd | 60 | 94 | 153.9295974(11) | 25.9(2) s | β$^−$ | $^{154}$Pm | 0+ | | |
| $^{154m}$Nd | 1297.9(4) keV | 1297.9(4) keV | 1297.9(4) keV | 3.2(3) μs | IT | $^{154}$Nd | (4−) | | |
| $^{155}$Nd | 60 | 95 | 154.9331356(98) | 8.9(2) s | β$^−$ | $^{155}$Pm | (3/2−) | | |
| $^{156}$Nd | 60 | 96 | 155.9353704(14) | 5.06(13) s | β$^−$ | $^{156}$Pm | 0+ | | |
| $^{156m}$Nd | 1431.3(4) keV | 1431.3(4) keV | 1431.3(4) keV | 365(145) ns | IT | $^{156}$Nd | 5− | | |
| $^{157}$Nd | 60 | 97 | 156.9393511(23) | 1.17(4) s | β$^−$ | $^{157}$Pm | 5/2−# | | |
| $^{158}$Nd | 60 | 98 | 157.9422056(14) | 810(30) ms | β$^−$ | $^{158}$Pm | 0+ | | |
| $^{158m}$Nd | 1648.1(14) keV | 1648.1(14) keV | 1648.1(14) keV | 339(20) ns | IT | $^{158}$Nd | (6−) | | |
| $^{159}$Nd | 60 | 99 | 158.946619(32) | 500(30) ms | β$^−$ | $^{159}$Pm | 7/2+# | | |
| $^{160}$Nd | 60 | 100 | 159.949839(50) | 439(37) ms | β$^−$ | $^{160}$Pm | 0+ | | |
| $^{160m}$Nd | 1107.9(9) keV | 1107.9(9) keV | 1107.9(9) keV | 1.63(21) μs | IT | $^{160}$Nd | (4−) | | |
| $^{161}$Nd | 60 | 101 | 160.95466(43)# | 215(76) ms | β$^−$ | $^{161}$Pm | 1/2−# | | |
| $^{162}$Nd | 60 | 102 | 161.95812(43)# | 310(200) ms | β$^−$ | $^{162}$Pm | 0+ | | |
| $^{163}$Nd | 60 | 103 | 162.96341(54)# | 80# ms [>550 ns] | | | 5/2−# | | |
| This table header & footer: view ||||||||||
* ↑ $^m$Nd – Excited nuclear isomer.
* ↑ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
* ↑ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
* ↑ Bold half-life – nearly stable, half-life longer than age of universe.
* 1 2 3 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
* ↑ Modes of decay: EC:Electron capture IT:Isomeric transition p:Proton emission
* ↑ Bold symbol as daughter – Daughter product is stable.
* ↑ ( ) spin value – Indicates spin with weak assignment arguments.
* 1 2 3 4 5 6 7 8 Fission product
* ↑ Believed to undergo α decay to $^{139}$Ce with a half-life over 1.1×10$^{20}$ years
* 1 2 Primordial radionuclide
* ↑ Believed to undergo α decay to $^{141}$Ce with a half-life of over 6.1×10$^{19}$ years
* ↑ Believed to undergo β$^−$β$^−$ decay to $^{146}$Sm, or α decay to $^{142}$Ce with a half-life of over 3.3×10$^{21}$ years
* ↑ Believed to undergo β$^−$β$^−$ decay to $^{148}$Sm with a half-life over 3×10$^{18}$ years, or α decay to $^{144}$Ce with a half-life of over 1.2×10$^{19}$ years