Isotopes of niobium

Naturally occurring niobium (Nb), element 41, is composed of one stable isotope (⁹³Nb). ⁹³Nb is the lightest nuclide theoretically susceptible to spontaneous fission, and although this has never been observed, it makes niobium theoretically the lightest element with no stable isotope. The first 40 elements (to zirconium) all have at least one stable nuclide susceptible in theory only to proton decay.

The most stable radioisotope is ⁹²Nb with a half-life of 34.7 million years. This nuclide is the longest-lived radionuclide of all elements that has not yet been detected in nature as a primordial isotope.^[1] (The nuclide with the next longest half-life, ¹⁴⁶Sm with half-life 68 million years, has been detected, and is thus primordial).

The next longest-lived niobium nuclides are ⁹⁴Nb (half-life: 20,300 years), and ⁹¹Nb with a half-life of 680 years. There is also a meta state at 31 keV whose half-life is 16.13 years. Twenty three 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 the stable ⁹³Nb is electron capture and the primary mode after is beta emission with some neutron emission occurring in ^104–110Nb.

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 halflife alone. Tiny amounts of the other isotopes may be produced as direct fission products.

Niobium's relative atomic mass is 92.90638(2).

Table

1. ↑ Abbreviations:
   EC: Electron capture
   IT: Isomeric transition
2. ↑ Bold for stable isotopes, bold italic for near-stable isotopes (half-life longer than the age of the universe)
3. ↑ Longest half-life of all non-primordial radionuclides
4. ↑ Theoretically capable of spontaneous fission, lightest nuclide so capable

Notes

• Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
• Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC, which use expanded uncertainties.

References

1. ↑ There are many shorter-lived radioisotopes in nature, but they are all cosmogenic or radiogenic
2. ↑ "Universal Nuclide Chart". nucleonica. (registration required (help)). 

• Isotope masses from:
  • G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). 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:
  • J. R. de Laeter; J. K. Böhlke; P. De Bièvre; H. Hidaka; H. S. Peiser; K. J. R. Rosman; P. D. P. Taylor (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683. 
  • M. E. Wieser (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051. Lay summary. 
• Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
  • G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. 
  • National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. Retrieved September 2005.  Check date values in: |access-date= (help)
  • N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide. CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0-8493-0485-9. 

Isotopes of the chemical elements
1 H																	2 He
3 Li	4 Be											5 B	6 C	7 N	8 O	9 F	10 Ne
11 Na	12 Mg											13 Al	14 Si	15 P	16 S	17 Cl	18 Ar
19 K	20 Ca	21 Sc	22 Ti	23 V	24 Cr	25 Mn	26 Fe	27 Co	28 Ni	29 Cu	30 Zn	31 Ga	32 Ge	33 As	34 Se	35 Br	36 Kr
37 Rb	38 Sr	39 Y	40 Zr	41 Nb	42 Mo	43 Tc	44 Ru	45 Rh	46 Pd	47 Ag	48 Cd	49 In	50 Sn	51 Sb	52 Te	53 I	54 Xe
55 Cs	56 Ba		72 Hf	73 Ta	74 W	75 Re	76 Os	77 Ir	78 Pt	79 Au	80 Hg	81 Tl	82 Pb	83 Bi	84 Po	85 At	86 Rn
87 Fr	88 Ra		104 Rf	105 Db	106 Sg	107 Bh	108 Hs	109 Mt	110 Ds	111 Rg	112 Cn	113 Nh	114 Fl	115 Mc	116 Lv	117 Ts	118 Og
		57 La	58 Ce	59 Pr	60 Nd	61 Pm	62 Sm	63 Eu	64 Gd	65 Tb	66 Dy	67 Ho	68 Er	69 Tm	70 Yb	71 Lu
		89 Ac	90 Th	91 Pa	92 U	93 Np	94 Pu	95 Am	96 Cm	97 Bk	98 Cf	99 Es	100 Fm	101 Md	102 No	103 Lr
Table of nuclides Categories: Isotopes Tables of nuclides Metastable isotopes Isotopes by element