Isotopes of niobium

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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 which is 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, 244Pu with half-life 80 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 standard atomic mass is 92.90638(2) u.

Table[edit]

nuclide
symbol
Z(p) N(n)  
isotopic mass (u)
 
half-life decay
mode(s)[2][n 1]
daughter
isotope(s)[n 2]
nuclear
spin
representative
isotopic
composition
(mole fraction)
range of natural
variation
(mole fraction)
excitation energy
81Nb 41 40 80.94903(161)# <44 ns β+, p 80Y 3/2-#
p 80Zr
β+ 81Zr
82Nb 41 41 81.94313(32)# 51(5) ms β+ 82Zr 0+
83Nb 41 42 82.93671(34) 4.1(3) s β+ 83Zr (5/2+)
84Nb 41 43 83.93357(32)# 9.8(9) s β+ (>99.9%) 84Zr 3+
β+, p (<.1%) 83Y
84mNb 338(10) keV 103(19) ns (5-)
85Nb 41 44 84.92791(24) 20.9(7) s β+ 85Zr (9/2+)
85mNb 759.0(10) keV 12(5) s (1/2-)
86Nb 41 45 85.92504(9) 88(1) s β+ 86Zr (6+)
86mNb 250(160)# keV 56(8) s β+ 86Zr high
87Nb 41 46 86.92036(7) 3.75(9) min β+ 87Zr (1/2-)
87mNb 3.84(14) keV 2.6(1) min β+ 87Zr (9/2+)#
88Nb 41 47 87.91833(11) 14.55(6) min β+ 88Zr (8+)
88mNb 40(140) keV 7.8(1) min β+ 88Zr (4-)
89Nb 41 48 88.913418(29) 2.03(7) h β+ 89Zr (9/2+)
89mNb 0(30)# keV 1.10(3) h β+ 89Zr (1/2)-
90Nb 41 49 89.911265(5) 14.60(5) h β+ 90Zr 8+
90m1Nb 122.370(22) keV 63(2) µs 6+
90m2Nb 124.67(25) keV 18.81(6) s IT 90Nb 4-
90m3Nb 171.10(10) keV <1 µs 7+
90m4Nb 382.01(25) keV 6.19(8) ms 1+
90m5Nb 1880.21(20) keV 472(13) ns (11-)
91Nb 41 50 90.906996(4) 680(130) a EC (99.98%) 91Zr 9/2+
β+ (.013%) 91Zr
91m1Nb 104.60(5) keV 60.86(22) d IT (93%) 91Nb 1/2-
EC (7%) 91Zr
β+ (.0028%) 91Zr
91m2Nb 2034.35(19) keV 3.76(12) µs (17/2-)
92Nb 41 51 91.907194(3) 3.47(24)×107 a[n 3] β+ (99.95%) 92Zr (7)+
β- (.05%) 92Mo
92m1Nb 135.5(4) keV 10.15(2) d β+ 92Zr (2)+
92m2Nb 225.7(4) keV 5.9(2) µs (2)-
92m3Nb 2203.3(4) keV 167(4) ns (11-)
93Nb 41 52 92.9063781(26) Stable[n 4] 9/2+ 1.0000
93mNb 30.77(2) keV 16.13(14) a IT 93Nb 1/2-
94Nb 41 53 93.9072839(26) 2.03(16)×104 a β- 94Mo (6)+
94mNb 40.902(12) keV 6.263(4) min IT (99.5%) 94Nb 3+
β- (.5%) 94Mo
95Nb 41 54 94.9068358(21) 34.991(6) d β- 95Mo 9/2+
95mNb 235.690(20) keV 3.61(3) d IT (94.4%) 95Nb 1/2-
β- (5.6%) 95Mo
96Nb 41 55 95.908101(4) 23.35(5) h β- 96Mo 6+
97Nb 41 56 96.9080986(27) 72.1(7) min β- 97Mo 9/2+
97mNb 743.35(3) keV 52.7(18) s IT 97Nb 1/2-
98Nb 41 57 97.910328(6) 2.86(6) s β- 98Mo 1+
98mNb 84(4) keV 51.3(4) min β- (99.9%) 98Mo (5+)
IT (.1%) 98Nb
99Nb 41 58 98.911618(14) 15.0(2) s β- 99Mo 9/2+
99mNb 365.29(14) keV 2.6(2) min β- (96.2%) 99Mo 1/2-
IT (3.8%) 99Nb
100Nb 41 59 99.914182(28) 1.5(2) s β- 100Mo 1+
100mNb 470(40) keV 2.99(11) s β- 100Mo (4+,5+)
101Nb 41 60 100.915252(20) 7.1(3) s β- 101Mo (5/2#)+
102Nb 41 61 101.91804(4) 1.3(2) s β- 102Mo 1+
102mNb 130(50) keV 4.3(4) s β- 102Mo high
103Nb 41 62 102.91914(7) 1.5(2) s β- 103Mo (5/2+)
104Nb 41 63 103.92246(11) 4.9(3) s β- (99.94%) 104Mo (1+)
β-, n (.06%) 103Mo
104mNb 220(120) keV 940(40) ms β- (99.95%) 104Mo high
β-, n (.05%) 103Mo
105Nb 41 64 104.92394(11) 2.95(6) s β- (98.3%) 105Mo (5/2+)#
β-, n (1.7%) 104Mo
106Nb 41 65 105.92797(21)# 920(40) ms β- (95.5%) 106Mo 2+#
β-, n (4.5%) 105Mo
107Nb 41 66 106.93031(43)# 300(9) ms β- (94%) 107Mo 5/2+#
β-, n (6%) 106Mo
108Nb 41 67 107.93484(32)# 0.193(17) s β- (93.8%) 108Mo (2+)
β-, n (6.2%) 107Mo
109Nb 41 68 108.93763(54)# 190(30) ms β- (69%) 109Mo 5/2+#
β-, n (69%) 108Mo
110Nb 41 69 109.94244(54)# 170(20) ms β- (60%) 110Mo 2+#
β-, n (40%) 109Mo
111Nb 41 70 110.94565(54)# 80# ms [>300 ns] 5/2+#
112Nb 41 71 111.95083(75)# 60# ms [>300 ns] 2+#
113Nb 41 72 112.95470(86)# 30# ms [>300 ns] 5/2+#
  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[edit]

  • 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[edit]

  1. ^ There are many shorter-lived radioisotopes in nature, but they are all cosmogenic or radiogenic
  2. ^ http://www.nucleonica.net/unc.aspx


Isotopes of zirconium Isotopes of niobium Isotopes of molybdenum
Table of nuclides