Isotopes of niobium

Naturally occurring niobium (₄₁Nb) is composed of one stable isotope (⁹³Nb). The most stable radioisotope is ⁹²Nb with a half-life of 34.7 million years. The next longest-lived niobium isotopes are ⁹⁴Nb (half-life: 20,300 years) and ⁹¹Nb with a half-life of 680 years. There is also a meta state of ⁹³Nb at 31 keV whose half-life is 16.13 years. Twenty-seven other radioisotopes have been characterized. Most of these have half-lives that are less than two hours, except ⁹⁵Nb (35 days), ⁹⁶Nb (23.4 hours) and ⁹⁰Nb (14.6 hours). The primary decay mode before stable ⁹³Nb is electron capture and the primary mode after is beta emission with some neutron emission occurring in ^104–110Nb.

Isotopes of niobium (₄₁Nb)

Main isotopes[1] Decay abun­dance half-life (t1/2) mode pro­duct 91Nb synth 680 y ε 91Zr 92Nb trace 3.47×107 y β+ 92Zr 93Nb 100% stable 93mNb synth 16.12 y IT 93Nb 94Nb trace 2.04×104 y β− 94Mo 95Nb synth 34.991 d β− 95Mo
Standard atomic weight Ar°(Nb)
	92.90637±0.00001[2] 92.906±0.001 (abridged)[3]
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Only ⁹⁵Nb (35 days) and ⁹⁷Nb (72 minutes) and heavier isotopes (half-lives in seconds) are fission products in significant quantity, as the other isotopes are shadowed by stable or very long-lived (⁹³Zr) isotopes of the preceding element zirconium from production via beta decay of neutron-rich fission fragments. ⁹⁵Nb is the decay product of ⁹⁵Zr (64 days), so disappearance of ⁹⁵Nb in used nuclear fuel is slower than would be expected from its own 35-day half-life alone. Small amounts of other isotopes may be produced as direct fission products.

List of isotopes

Nuclide [n 1]	Z	N	Isotopic mass (Da)[4] [n 2][n 3]	Half-life[1] [n 4]	Decay mode[1] [n 5]	Daughter isotope [n 6][n 7]	Spin and parity[1] [n 8][n 4]	Isotopic abundance
	Excitation energy[n 4]
82Nb	41	41	81.94438(32)	51(5) ms	β+	82Zr	(0+)
82mNb	1180(1) keV			93(20) ns	IT	82Nb	(5+)
83Nb	41	42	82.93815(17)	3.9(2) s	β+	83Zr	9/2+#
84Nb	41	43	83.93430571(43)	9.8(9) s	β+	84Zr	(1+)
84m2Nb	48(1) keV			176(46) ns	IT	84Nb	(3+)
84m2Nb	337.7(4) keV			92(5) ns	IT	84Nb	(5−)
85Nb	41	44	84.9288458(44)	20.5(7) s	β+	85Zr	9/2+#
85mNb	150(80)# keV			3.3(9) s	IT (?%)	85Nb	(1/2−)
					β+ (?%)	85Zr
86Nb	41	45	85.9257815(59)	88(1) s	β+	86Zr	(6+)
86mNb[n 9]	150(100)# keV			20# s	β+	86Zr	(0−,1−,2−)
87Nb	41	46	86.9206925(73)	3.7(1) min	β+	87Zr	(1/2)−
87mNb	3.9(1) keV			2.6(1) min	β+	87Zr	(9/2)+
88Nb	41	47	87.918226(62)	14.50(11) min	β+	88Zr	(8+)
88mNb[n 9]	130(120) keV			7.7(1) min	β+	88Zr	(4−)
89Nb	41	48	88.913445(25)	2.03(7) h	β+	89Zr	(9/2+)
89mNb[n 9]	0(30)# keV			1.10(3) h	β+	89Zr	(1/2)−
90Nb	41	49	89.9112592(36)	14.60(5) h	β+	90Zr	8+
90m1Nb	122.370(22) keV			63(2) μs	IT	90Nb	6+
90m2Nb	124.67(25) keV			18.81(6) s	IT	90Nb	4-
90m3Nb	171.10(10) keV			<1 μs	IT	90Nb	7+
90m4Nb	382.01(25) keV			6.19(8) ms	IT	90m1Nb	1+
90m5Nb	1880.21(20) keV			471(6) ns	IT	90Nb	(11−)
91Nb	41	50	90.9069903(31)	680(130) y	EC (99.99%)	91Zr	9/2+
					β+ (0.0138%)
91m1Nb	104.60(5) keV			60.86(22) d	IT (96.6%)	91Nb	1/2−
					EC (3.4%)	91Zr
					β+ (.0028%)
91m2Nb	2034.42(20) keV			3.76(12) μs	IT	91Nb	(17/2−)
92Nb	41	51	91.9071886(19)	3.47(24)×107 y	β+	92Zr	7+	Trace
92m1Nb	135.5(4) keV			10.116(13) d	β+	92Zr	(2)+
92m2Nb	225.8(4) keV			5.9(2) μs	IT	92Nb	(2)−
92m3Nb	2203.3(4) keV			167(4) ns	IT	92Nb	(11−)
93Nb	41	52	92.9063732(16)	Stable			9/2+	1.0000
93m1Nb	30.760(5) keV			16.12(12) y	IT	93Nb	1/2−
93m2Nb	7460(17) keV			1.5(5) μs	IT	93Nb	33/2−#
94Nb	41	53	93.9072790(16)	2.04(4)×104 y	β−	94Mo	6+	Trace
94mNb	40.892(12) keV			6.263(4) min	IT (99.50%)	94Nb	3+
					β− (0.50%)	94Mo
95Nb	41	54	94.90683111(55)	34.991(6) d	β−	95Mo	9/2+
95mNb	235.69(2) keV			3.61(3) d	IT (94.4%)	95Nb	1/2−
					β− (5.6%)	95Mo
96Nb	41	55	95.90810159(16)	23.35(5) h	β−	96Mo	6+
97Nb	41	56	96.9081016(46)	72.1(7) min	β−	97Mo	9/2+
97mNb	743.35(3) keV			58.7(18) s	IT	97Nb	1/2−
98Nb	41	57	97.9103326(54)	2.86(6) s	β−	98Mo	1+
98mNb	84(4) keV			51.1(4) min	β−	98Mo	(5)+
99Nb	41	58	98.911609(13)	15.0(2) s	β−	99Mo	9/2+
99mNb	365.27(8) keV			2.5(2) min	β− (?%)	99Mo	1/2−
					IT (?%)	99Nb
100Nb	41	59	99.9143406(86)	1.5(2) s	β−	100Mo	1+
100m1Nb	313(8) keV			2.99(11) s	β−	100Mo	(5+)
100m2Nb	347(8) keV			460(60) ns	IT	100Nb	(4−,5−)
100m3Nb	734(8) keV			12.43(26) μs	IT	100Nb	(8−)
101Nb	41	60	100.9153065(40)	7.1(3) s	β−	101Mo	5/2+
102Nb	41	61	101.9180904(27)	4.3(4) s	β−	102Mo	(4+)
102mNb	94(7) keV			1.31(16) s	β−	102Mo	(1+)
103Nb	41	62	102.9194534(42)	1.34(7) s	β−	103Mo	5/2+
104Nb	41	63	103.9229077(19)	0.98(5) s	β− (99.95%)	104Mo	(1+)
					β−, n (0.05%)	103Mo
104mNb[n 9]	9.8(26) keV			4.9(3) s	β− (99.94%)	104Mo	(0−,1−)
					β−, n (0.06%)	103Mo
105Nb	41	64	104.9249426(43)	2.91(5) s	β− (98.3%)	105Mo	(5/2+)
					β−, n (1.7%)	104Mo
106Nb	41	65	105.9289285(15)	900(20) ms	β− (95.5%)	106Mo	1−#
					β−, n (4.5%)	105Mo
106m1Nb	100(50)# keV			1.20(6) s	β−	106Mo	(4−)
106m2Nb	204.8(5) keV			820(38) ns	IT	106Nb	(3+)
107Nb	41	66	106.9315897(86)	286(8) ms	β− (92.6%)	107Mo	(5/2+)
					β−, n (7.4%)	106Mo
108Nb	41	67	107.9360756(88)	201(4) ms	β− (93.7%)	108Mo	(2+)
					β−, n (6.3%)	107Mo
108mNb	166.6(5) keV			109(2) ns	IT	109Nb	6−#
109Nb	41	68	108.93914(46)	106.9(49) ms	β− (69%)	109Mo	3/2−#
					β−, n (31%)	108Mo
109mNb	312.5(4) keV			115(8) ns	IT	109Nb	7/2+#
110Nb	41	69	109.94384(90)	75(1) ms	β− (60%)	110Mo	5+#
					β−, n (40%)	109Mo
110mNb[n 9]	100(50)# keV			94(9) ms	β− (60%)	104Mo	2+#
					β−, n (40%)	103Mo
111Nb	41	70	110.94744(32)#	54(2) ms	β−	111Mo	3/2−#
112Nb	41	71	111.95269(32)#	38(2) ms	β−	112Mo	1+#
113Nb	41	72	112.95683(43)#	32(4) ms	β−	113Mo	3/2−#
114Nb	41	73	113.96247(54)#	17(5) ms	β−	114Mo	2−#
115Nb	41	74	114.96685(54)#	23(8) ms	β−	115Mo	3/2−#
116Nb	41	75	115.97291(32)#	12# ms [>550 ns]			1−#
117Nb[5]	41	76
This table header & footer: view

1. ^mNb – 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. # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
5. Modes of decay:

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

6. Bold italics symbol as daughter – Daughter product is nearly stable.
7. Bold symbol as daughter – Daughter product is stable.
8. ( ) spin value – Indicates spin with weak assignment arguments.
9. Order of ground state and isomer is uncertain.

Niobium-92

Niobium-92 is an extinct radionuclide^[6] with a half-life of 34.7 million years, decaying predominantly via β⁺ decay. Its abundance relative to the stable ⁹³Nb in the early Solar System, estimated at 1.7×10⁻⁵, has been measured to investigate the origin of p-nuclei.^[6][7] A higher initial abundance of ⁹²Nb has been estimated for material in the outer protosolar disk (sampled from the meteorite NWA 6704), suggesting that this nuclide was predominantly formed via the gamma process (photodisintegration) in a nearby core-collapse supernova.^[8]

Niobium-92, along with niobium-94, has been detected in refined samples of terrestrial niobium and may originate from bombardment by cosmic ray muons in Earth's crust.^[9]

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: Niobium". CIAAW. 2017.
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. Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.
5. Sumikama, T.; et al. (2021). "Observation of new neutron-rich isotopes in the vicinity of Zr110". Physical Review C. 103 (1): 014614. Bibcode:2021PhRvC.103a4614S. doi:10.1103/PhysRevC.103.014614. hdl:10261/260248. S2CID 234019083.
6. Iizuka, Tsuyoshi; Lai, Yi-Jen; Akram, Waheed; Amelin, Yuri; Schönbächler, Maria (2016). "The initial abundance and distribution of ⁹²Nb in the Solar System". Earth and Planetary Science Letters. 439: 172–181. arXiv:1602.00966. Bibcode:2016E&PSL.439..172I. doi:10.1016/j.epsl.2016.02.005. S2CID 119299654.
7. Hibiya, Y; Iizuka, T; Enomoto, H (2019). THE INITIAL ABUNDANCE OF NIOBIUM-92 IN THE OUTER SOLAR SYSTEM (PDF). Lunar and Planetary Science Conference (50th ed.). Retrieved 7 September 2019.
8. Hibiya, Y.; Iizuka, T.; Enomoto, H.; Hayakawa, T. (2023). "Evidence for enrichment of niobium-92 in the outer protosolar disk". Astrophysical Journal Letters. 942 (L15): L15. Bibcode:2023ApJ...942L..15H. doi:10.3847/2041-8213/acab5d. S2CID 255414098.
9. Clayton, Donald D.; Morgan, John A. (1977). "Muon production of ^92,94Nb in the Earth's crust". Nature. 266 (5604): 712–713. doi:10.1038/266712a0. S2CID 4292459.

• 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.