Isotopes of niobium

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Naturally occurring niobium (Nb) is composed of one stable isotope (Nb-93). The most stable radioisotopes are Nb-92 with a half-life of 34.7 million years, Nb-94 (half life: 20300 years), and Nb-91 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 Nb-95 (35 days), Nb-96 (23.4 hours) and Nb-90 (14.6 hours). The primary decay mode before the stable Nb-93 is electron capture and the primary mode after is beta emission with some neutron emission occurring in the first mode of the two mode decay of Nb-104, 109 and 110.

Only Nb-95 (35 days) and Nb-97 (72 minutes) and heavier isotopes (halflives in seconds) are fission products in significant quantity, as the other isotopes are shadowed by stable or very long-lived (Zr-93) isotopes of the preceding element zirconium from production via beta decay of neutron-rich fission fragments. Nb-95 is the decay product of Zr-95 (64 days), so disappearance of Nb-95 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.
Standard atomic mass: 92.90638(2) u

[edit] Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
nuclide symbol	excitation energy			half-life	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
⁸¹Nb	41	40	80.94903(161)#	<44 ns	3/2-#
⁸²Nb	41	41	81.94313(32)#	51(5) ms	0+
⁸³Nb	41	42	82.93671(34)	4.1(3) s	(5/2+)
⁸⁴Nb	41	43	83.93357(32)#	9.8(9) s	3+
^84mNb	338(10) keV			103(19) ns	(5-)
⁸⁵Nb	41	44	84.92791(24)	20.9(7) s	(9/2+)
^85mNb	759.0(10) keV			12(5) s	(1/2-)
⁸⁶Nb	41	45	85.92504(9)	88(1) s	(6+)
^86mNb	250(160)# keV			56(8) s	high
⁸⁷Nb	41	46	86.92036(7)	3.75(9) min	(1/2-)
^87mNb	3.84(14) keV			2.6(1) min	(9/2+)#
⁸⁸Nb	41	47	87.91833(11)	14.55(6) min	(8+)
^88mNb	40(140) keV			7.8(1) min	(4-)
⁸⁹Nb	41	48	88.913418(29)	2.03(7) h	(9/2+)
^89mNb	0(30)# keV			1.10(3) h	(1/2)-
⁹⁰Nb	41	49	89.911265(5)	14.60(5) h	8+
^90m1Nb	122.370(22) keV			63(2) µs	6+
^90m2Nb	124.67(25) keV			18.81(6) s	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	9/2+
^91m1Nb	104.60(5) keV			60.86(22) d	1/2-
^91m2Nb	2034.35(19) keV			3.76(12) µs	(17/2-)
⁹²Nb	41	51	91.907194(3)	3.47(24)E+7 a	(7)+
^92m1Nb	135.5(4) keV			10.15(2) d	(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	9/2+	1.0000
^93mNb	30.77(2) keV			16.13(14) a	1/2-
⁹⁴Nb	41	53	93.9072839(26)	2.03(16)E+4 a	(6)+
^94mNb	40.902(12) keV			6.263(4) min	3+
⁹⁵Nb	41	54	94.9068358(21)	34.991(6) d	9/2+
^95mNb	235.690(20) keV			3.61(3) d	1/2-
⁹⁶Nb	41	55	95.908101(4)	23.35(5) h	6+
⁹⁷Nb	41	56	96.9080986(27)	72.1(7) min	9/2+
^97mNb	743.35(3) keV			52.7(18) s	1/2-
⁹⁸Nb	41	57	97.910328(6)	2.86(6) s	1+
^98mNb	84(4) keV			51.3(4) min	(5+)
⁹⁹Nb	41	58	98.911618(14)	15.0(2) s	9/2+
^99mNb	365.29(14) keV			2.6(2) min	1/2-
¹⁰⁰Nb	41	59	99.914182(28)	1.5(2) s	1+
^100mNb	470(40) keV			2.99(11) s	(4+,5+)
¹⁰¹Nb	41	60	100.915252(20)	7.1(3) s	(5/2#)+
¹⁰²Nb	41	61	101.91804(4)	1.3(2) s	1+
^102mNb	130(50) keV			4.3(4) s	high
¹⁰³Nb	41	62	102.91914(7)	1.5(2) s	(5/2+)
¹⁰⁴Nb	41	63	103.92246(11)	4.9(3) s	(1+)
^104mNb	220(120) keV			940(40) ms	high
¹⁰⁵Nb	41	64	104.92394(11)	2.95(6) s	(5/2+)#
¹⁰⁶Nb	41	65	105.92797(21)#	920(40) ms	2+#
¹⁰⁷Nb	41	66	106.93031(43)#	300(9) ms	5/2+#
¹⁰⁸Nb	41	67	107.93484(32)#	0.193(17) s	(2+)
¹⁰⁹Nb	41	68	108.93763(54)#	190(30) ms	5/2+#
¹¹⁰Nb	41	69	109.94244(54)#	170(20) ms	2+#
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+#

[edit] 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.

[edit] References

Isotope masses from Ame2003 Atomic Mass Evaluation by G. Audi, A.H. Wapstra, C. Thibault, J. Blachot and O. Bersillon in Nuclear Physics A729 (2003).
Isotopic compositions and standard atomic masses from Atomic weights of the elements. Review 2000 (IUPAC Technical Report). Pure Appl. Chem. Vol. 75, No. 6, pp. 683-800, (2003) and Atomic Weights Revised (2005).
Half-life, spin, and isomer data selected from these sources. Editing notes on this article's talk page.
- Audi, Bersillon, Blachot, Wapstra. The Nubase2003 evaluation of nuclear and decay properties, Nuc. Phys. A 729, pp. 3-128 (2003).
- National Nuclear Data Center, Brookhaven National Laboratory. Information extracted from the NuDat 2.1 database (retrieved Sept. 2005).
- David R. Lide (ed.), Norman E. Holden in CRC Handbook of Chemistry and Physics, 85th Edition, online version. CRC Press. Boca Raton, Florida (2005). Section 11, Table of the Isotopes.