Isotopes of neodymium

Naturally occurring neodymium (₆₀Nd) is composed of five stable isotopes, ¹⁴²Nd, ¹⁴³Nd, ¹⁴⁵Nd, ¹⁴⁶Nd and ¹⁴⁸Nd, with ¹⁴²Nd being the most abundant (27.2% natural abundance), and two long-lived radioisotopes, ¹⁴⁴Nd and ¹⁵⁰Nd. In all, 35 radioisotopes of neodymium have been characterized up to now, with the most stable being naturally occurring isotopes ¹⁴⁴Nd (alpha decay, a half-life (t_1/2) of 2.29×10¹⁵ years) and ¹⁵⁰Nd (double beta decay, t_1/2 of 9.3×10¹⁸ 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 ¹⁴⁷Nd with a half-life of 10.98 days. This element also has 15 known meta states with the most stable being ^139mNd (t_1/2 5.5 hours), ^135mNd (t_1/2 5.5 minutes) and ^133m1Nd (t_1/2 ~70 seconds).

Isotopes of neodymium (₆₀Nd)

Main isotopes[1] Decay abun­dance half-life (t1/2) mode pro­duct 142Nd 27.2% stable 143Nd 12.2% stable 144Nd 23.8% 2.29×1015 y α 140Ce 145Nd 8.3% stable 146Nd 17.2% stable 148Nd 5.80% stable 150Nd 5.60% 9.3×1018 y[1] β−β− 150Sm
Standard atomic weight Ar°(Nd)
	144.242±0.003[2] 144.24±0.01 (abridged)[3]
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The primary decay modes for isotopes lighter than the most abundant stable isotope (also the only theoretically stable isotope), ¹⁴²Nd, 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.^[4][5][6]

List of isotopes

Nuclide [n 1]	Z	N	Isotopic mass (Da) [n 2][n 3]	Half-life [n 4][n 5]	Decay mode [n 6]	Daughter isotope [n 7]	Spin and parity [n 8][n 5]	Natural abundance (mole fraction)
	Excitation energy[n 5]							Normal proportion	Range of variation
124Nd	60	64	123.95223(64)#	500# ms			0+
125Nd	60	65	124.94888(43)#	600(150) ms			5/2(+#)
126Nd	60	66	125.94322(43)#	1# s [>200 ns]	β+	126Pr	0+
127Nd	60	67	126.94050(43)#	1.8(4) s	β+	127Pr	5/2+#
					β+, p (rare)	126Ce
128Nd	60	68	127.93539(21)#	5# s	β+	128Pr	0+
					β+, p (rare)	127Ce
129Nd	60	69	128.93319(22)#	4.9(2) s	β+	129Pr	5/2+#
					β+, p (rare)	128Ce
130Nd	60	70	129.92851(3)	21(3) s	β+	130Pr	0+
131Nd	60	71	130.92725(3)	33(3) s	β+	131Pr	(5/2)(+#)
					β+, p (rare)	130Ce
132Nd	60	72	131.923321(26)	1.56(10) min	β+	132Pr	0+
133Nd	60	73	132.92235(5)	70(10) s	β+	133Pr	(7/2+)
133m1Nd	127.97(11) keV			~70 s	β+	133Pr	(1/2)+
133m2Nd	176.10(10) keV			~300 ns			(9/2–)
134Nd	60	74	133.918790(13)	8.5(15) min	β+	134Pr	0+
134mNd	2293.1(4) keV			410(30) μs			(8)–
135Nd	60	75	134.918181(21)	12.4(6) min	β+	135Pr	9/2(–)
135mNd	65.0(2) keV			5.5(5) min	β+	135Pr	(1/2+)
136Nd	60	76	135.914976(13)	50.65(33) min	β+	136Pr	0+
137Nd	60	77	136.914567(12)	38.5(15) min	β+	137Pr	1/2+
137mNd	519.43(17) keV			1.60(15) s	IT	137Nd	(11/2–)
138Nd	60	78	137.911950(13)	5.04(9) h	β+	138Pr	0+
138mNd	3174.9(4) keV			410(50) ns			(10+)
139Nd	60	79	138.911978(28)	29.7(5) min	β+	139Pr	3/2+
139m1Nd	231.15(5) keV			5.50(20) h	β+ (88.2%)	139Pr	11/2–
					IT (11.8%)	139Nd
139m2Nd	2570.9+X keV			≥141 ns
140Nd	60	80	139.90955(3)	3.37(2) d	EC	140Pr	0+
140mNd	2221.4(1) keV			600(50) μs			7–
141Nd	60	81	140.909610(4)	2.49(3) h	β+	141Pr	3/2+
141mNd	756.51(5) keV			62.0(8) s	IT (99.95%)	141Nd	11/2–
					β+ (.05%)	141Pr
142Nd	60	82	141.9077233(25)	Stable			0+	0.272(5)	0.2680–0.2730
143Nd[n 9]	60	83	142.9098143(25)	Observationally Stable[n 10]			7/2−	0.122(2)	0.1212–0.1232
144Nd[n 9][n 11]	60	84	143.9100873(25)	2.29(16)×1015 y	α	140Ce	0+	0.238(3)	0.2379–0.2397
145Nd[n 9]	60	85	144.9125736(25)	Observationally Stable[n 12]			7/2−	0.083(1)	0.0823–0.0835
146Nd[n 9]	60	86	145.9131169(25)	Observationally Stable[n 13]			0+	0.172(3)	0.1706–0.1735
147Nd[n 9]	60	87	146.9161004(25)	10.98(1) d	β−	147Pm	5/2−
148Nd[n 9]	60	88	147.916893(3)	Observationally Stable[n 14]			0+	0.057(1)	0.0566–0.0578
149Nd[n 9]	60	89	148.920149(3)	1.728(1) h	β−	149Pm	5/2−
150Nd[n 9][n 11][n 15]	60	90	149.920891(3)	9.3(7)×1018 y[1]	β−β−	150Sm	0+	0.056(2)	0.0553–0.0569
151Nd	60	91	150.923829(3)	12.44(7) min	β−	151Pm	3/2+
152Nd	60	92	151.924682(26)	11.4(2) min	β−	152Pm	0+
153Nd	60	93	152.927698(29)	31.6(10) s	β−	153Pm	(3/2)−
154Nd	60	94	153.92948(12)	25.9(2) s	β−	154Pm	0+
154m1Nd	480(150)# keV			1.3(5) μs
154m2Nd	1349(10) keV			>1 μs			(5−)
155Nd	60	95	154.93293(16)#	8.9(2) s	β−	155Pm	3/2−#
156Nd	60	96	155.93502(22)	5.49(7) s	β−	156Pm	0+
156mNd	1432(5) keV			135 ns			5−
157Nd	60	97	156.93903(21)#	1.17(4) s[9]	β−	157Pm	5/2−#
158Nd	60	98	157.94160(43)#	810(30) ms	β−	158Pm	0+
158mNd	1648.1(14) keV			339(20) ns	IT	160Nd	(6−)
159Nd	60	99	158.94609(54)#	500(30) ms	β−	159Pm	7/2+#
160Nd	60	100	159.94909(64)#	439(37) ms	β−	160Pm	0+
160mNd	1107.9(9) keV			1.63(21) μs	IT	160Nd	(4−)
161Nd	60	101	160.95388(75)#	215(76) ms	β−	161Pm	1/2−#
162Nd	60	102		310(200) ms	β−	162Pm	0+
163Nd	60	103		80# ms	β−	163Pm	5/2−#
This table header & footer: view

1. ^mNd – 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. Bold half-life – nearly stable, half-life longer than age of universe.
5. # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
6. Modes of decay:

   EC:	Electron capture
   IT:	Isomeric transition
   p:	Proton emission

7. Bold symbol as daughter – Daughter product is stable.
8. ( ) spin value – Indicates spin with weak assignment arguments.
9. Fission product
10. Believed to undergo α decay to ¹³⁹Ce with a half-life over 2.8×10¹⁹ years^[1][7][8]
11. Primordial radionuclide
12. Believed to undergo α decay to ¹⁴¹Ce with a half-life of over 6.1×10¹⁹ years^[1][7][8]
13. Believed to undergo β⁻β⁻ decay to ¹⁴⁶Sm or α decay to ¹⁴²Ce with a half-life of over 3.3×10²¹ years^[1][7][8]
14. Believed to undergo β⁻β⁻ decay to ¹⁴⁸Sm or α decay to ¹⁴⁴Ce with a half-life of over 1.2×10¹⁹ years^[1][7][8]
15. Predicted to be capable of undergoing triple beta decay and quadruple beta decay with very long partial half-lives

References

1. Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
2. "Standard Atomic Weights: Neodymium". CIAAW. 2005.
3. Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
4. Hemond, C.; Menet, C.; Menager, M.T. (1991). "U and Nd Isotopes from the New Oklo Reactor 10 (GABON): Evidence for Radioelements Migration". MRS Proceedings. 257. doi:10.1557/PROC-257-489.
5. "Oklo's Natural Nuclear Reactors". 24 October 2020.
6. "The Implications of the Oklo Phenomenon on the Constancy of Radiometric Decay Rates".
7. Sokur, N.V.; Belli, P.; Bernabei, R.; Boiko, R.S.; Cappella, F.; Caracciolo, V.; Cerulli, R.; Danevich, F.A.; Incicchitti, A.; Kasperovych, D.V.; Kobychev, V.V.; Laubenstein, M.; Leoncini, A.; Merlo, V.; Polischuk, O.G.; Tretyak, V.I. (11 July 2023). Alpha decay of naturally occurring neodymium isotopes. XII International Conference on New Frontiers in Physics.
8. Belli, P.; Bernabei, R.; Danevich, F. A.; Incicchitti, A.; Tretyak, V. I. (2019). "Experimental searches for rare alpha and beta decays". European Physical Journal A. 55 (140): 4–6. arXiv:1908.11458. Bibcode:2019EPJA...55..140B. doi:10.1140/epja/i2019-12823-2. S2CID 201664098.
9. Hartley, D. J.; Kondev, F. G.; Carpenter, M. P.; Clark, J. A.; Copp, P.; Kay, B.; Lauritsen, T.; Savard, G.; Seweryniak, D.; Wilson, G. L.; Wu, J. (2023-08-14). "First β⁻-decay spectroscopy study of ¹⁵⁷Nd". Physical Review C. 108 (2). American Physical Society (APS): 024307. Bibcode:2023PhRvC.108b4307H. doi:10.1103/physrevc.108.024307. ISSN 2469-9985. S2CID 260913513.

• Isotope masses from:
  • Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
• Isotopic compositions and standard atomic masses from:
  • de Laeter, John Robert; Böhlke, John Karl; De Bièvre, Paul; Hidaka, Hiroshi; Peiser, H. Steffen; Rosman, Kevin J. R.; Taylor, Philip D. P. (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
  • Wieser, Michael E. (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051.
• "News & Notices: Standard Atomic Weights Revised". International Union of Pure and Applied Chemistry. 19 October 2005.
• Half-life, spin, and isomer data selected from the following sources.
  • Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
  • National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
  • Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.