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. The radioactivity of ¹⁴⁴Nd is due to it having 84 neutrons (two more than 82, which is a magic number corresponding to a stable neutron configuration), and so it may emit an alpha particle (which has 2 neutrons) to form cerium-140 with 82 neutrons.

Isotopes of neodymium (₆₀Nd)

Main isotopes Decay Isotope abun­dance half-life (t1/2) mode pro­duct ^140Nd synth 3.37 d β^+ ^140Pr ^142Nd 27.2% stable ^143Nd 12.2% stable ^144Nd 23.8% 2.29×10^15 y α ^140Ce ^145Nd 8.3% stable ^146Nd 17.2% stable ^147Nd synth 10.98 d β^− ^147Pm ^148Nd 5.80% stable ^150Nd 5.60% 9.3×10^18 y β^−β^− ^150Sm
Standard atomic weight Ar°(Nd)
	144.242±0.003 144.24±0.01 (abridged)
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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, the parent of promethium, 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).

The primary decay modes for isotopes lighter than the lightest and most abundant stable isotope, which is 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.

List of isotopes

Nuclide	Z	N	Isotopic mass (Da)	Half-life	Decay mode	Daughter isotope	Spin and parity	Natural abundance (mole fraction)
	Excitation energy							Normal proportion	Range of variation
^125Nd	60	65	124.94840(43)#	0.65(15) s	β^+	^125Pr	(5/2)(+#)
					β^+, p (?%)	^124Ce
^126Nd	60	66	125.94269(32)#	1# s [>200 ns]			0+
^127Nd	60	67	126.93998(32)#	1.8(4) s	β^+	^127Pr	5/2+#
					β^+, p (?%)	^126Ce
^128Nd	60	68	127.93502(22)#	5# s			0+
^129Nd	60	69	128.93304(22)#	6.8(6) s	β^+	^129Pr	7/2−
					β^+, p (?%)	^128Ce
^129m1Nd	17 keV			2.6(4) s	β^+	^129Pr	1/2+
					β^+, p (?%)	^128Ce
^129m2Nd	39 keV			2.6(4) s	β^+	^129Pr	3/2+
					β^+, p (?%)	^128Ce
^129m3Nd	108 keV				IT (?%)	^129m2Nd	5/2+
					IT (?%)	^129Nd
^129m4Nd	1893 keV				IT	^129Nd	(17/2+)
^129m5Nd	2109 keV				IT	^129Nd	(19/2+)
^129m6Nd	2284 keV			0.48(4) μs	IT	^129Nd	(21/2+)
^130Nd	60	70	129.928506(30)	21(3) s	β^+	^130Pr	0+
^131Nd	60	71	130.927248(30)	25.4(9) s	β^+	^131Pr	(5/2+)
					β^+, p (?%)	^130Ce
^132Nd	60	72	131.923321(26)	1.56(10) min	β^+	^132Pr	0+
^133Nd	60	73	132.922348(50)	70(10) s	β^+	^133Pr	(7/2+)
^133m1Nd	127.97(12) keV			~70 s	β^+ (?%)	^133Pr	(1/2)+
					IT (?%)	^133Nd
^133m2Nd	176.10(10) keV			301(18) ns	IT	^133Nd	(9/2–)
^134Nd	60	74	133.918790(13)	8.5(15) min	β^+	^134Pr	0+
^134mNd	2293.0(4) keV			389(17) μs	IT	^134Nd	8–
^135Nd	60	75	134.918181(21)	12.4(6) min	β^+	^135Pr	9/2–
^135mNd	64.95(24) 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	136.914563(13)	38.5(15) min	β^+	^137Pr	1/2+
^137mNd	519.43(20) keV			1.60(15) s	IT	^137Nd	11/2–
^138Nd	60	78	137.911951(12)	5.04(9) h	β^+	^138Pr	0+
^138mNd	3174.5(4) keV			370(5) ns	IT	^138Nd	10+
^139Nd	60	79	138.911951(30)	29.7(5) min	β^+	^139Pr	3/2+
^139m1Nd	231.16(5) keV			5.50(20) h	β^+ (87.0%)	^139Pr	11/2–
					IT (13.0%)	^139Nd
^139m2Nd	2616.9(6) keV			276.8(18) ns	IT	^139Nd	23/2
^140Nd	60	80	139.9095461(35)	3.37(2) d	EC	^140Pr	0+
^140m1Nd	2221.65(9) keV			600(50) μs	IT	^140Nd	7–
^140m2Nd	7435.1(4) keV			1.22(6) μs	IT	^140Nd	20+
^141Nd	60	81	140.9096167(34)	2.49(3) h	EC (97.28%)	^141Pr	3/2+
					β^+ (2.72%)
^141mNd	756.51(5) keV			62.0(8) s	IT (99.97%)	^141Nd	11/2–
					β^+ (0.032%)	^141Pr
^142Nd	60	82	141.9077288(13)	Stable			0+	0.27153(40)
^143Nd	60	83	142.9098198(13)	Observationally Stable			7/2−	0.12173(26)
^144Nd	60	84	143.9100928(13)	2.29(16)×10^15 y	α	^140Ce	0+	0.23798(19)
^145Nd	60	85	144.9125792(14)	Observationally Stable			7/2−	0.08293(12)
^146Nd	60	86	145.9131225(14)	Observationally Stable			0+	0.17189(32)
^147Nd	60	87	146.9161060(14)	10.98(1) d	β^−	^147Pm	5/2−
^148Nd	60	88	147.9168990(22)	Observationally Stable			0+	0.05756(21)
^149Nd	60	89	148.9201546(22)	1.728(1) h	β^−	^149Pm	5/2−
^150Nd	60	90	149.9209013(12)	9.3(7)×10^18 y	β^−β^−	^150Sm	0+	0.05638(28)
^151Nd	60	91	150.9238394(12)	12.44(7) min	β^−	^151Pm	3/2+
^152Nd	60	92	151.924691(26)	11.4(2) min	β^−	^152Pm	0+
^153Nd	60	93	152.9277179(29)	31.6(10) s	β^−	^153Pm	(3/2)−
^153mNd	191.71(16) keV			1.10(4) μs	IT	^153Nd	(5/2)+
^154Nd	60	94	153.9295974(11)	25.9(2) s	β^−	^154Pm	0+
^154mNd	1297.9(4) keV			3.2(3) μs	IT	^154Nd	(4−)
^155Nd	60	95	154.9331356(98)	8.9(2) s	β^−	^155Pm	(3/2−)
^156Nd	60	96	155.9353704(14)	5.06(13) s	β^−	^156Pm	0+
^156mNd	1431.3(4) keV			365(145) ns	IT	^156Nd	5−
^157Nd	60	97	156.9393511(23)	1.17(4) s	β^−	^157Pm	5/2−#
^158Nd	60	98	157.9422056(14)	810(30) ms	β^−	^158Pm	0+
^158mNd	1648.1(14) keV			339(20) ns	IT	^158Nd	(6−)
^159Nd	60	99	158.946619(32)	500(30) ms	β^−	^159Pm	7/2+#
^160Nd	60	100	159.949839(50)	439(37) ms	β^−	^160Pm	0+
^160mNd	1107.9(9) keV			1.63(21) μs	IT	^160Nd	(4−)
^161Nd	60	101	160.95466(43)#	215(76) ms	β^−	^161Pm	1/2−#
^162Nd	60	102	161.95812(43)#	310(200) ms	β^−	^162Pm	0+
^163Nd	60	103	162.96341(54)#	80# ms [>550 ns]			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 1.1×10²⁰ years
11. Primordial radionuclide
12. Believed to undergo α decay to ¹⁴¹Ce with a half-life of over 6.1×10¹⁹ years
13. Believed to undergo β⁻β⁻ decay to ¹⁴⁶Sm, or α decay to ¹⁴²Ce with a half-life of over 3.3×10²¹ years
14. Believed to undergo β⁻β⁻ decay to ¹⁴⁸Sm with a half-life over 3×10¹⁸ years, or α decay to ¹⁴⁴Ce with a half-life of over 1.2×10¹⁹ years

See also

Daughter products other than neodymium

• Isotopes of samarium
• Isotopes of promethium
• Isotopes of praseodymium
• Isotopes of cerium