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Isotopes of gadolinium



Naturally occurring Gadolinium (Gd) is composed of 5 stable isotopes, 154Gd, 155Gd, 156Gd, 157Gd and 158Gd, and 2 radioisotopes, 152Gd and 160Gd, with 158Gd being the most abundant (24.84% natural abundance).

Additional recommended knowledge

Thirty radioisotopes have been characterized, with the most stable being 160Gd with a half-life of more than 1.3×1021 years (the decay has not been observed - only the lower limit on the half-life is known), alpha-decaying 152Gd with a half-life of 1.08×1014 years, and 150Gd with a half-life of 1.79×106 years. All of the remaining isotopes are radioactive, having half-lives less than 74.7 years. The majority of these have half-lives less than 24.6 seconds. Gadolinium isotopes have 4 metastable isomers, with the most stable being 143mGd (t½ 110 seconds), 145mGd (t½ 85 seconds) and 141mGd (t½ 24.5 seconds).

The primary decay mode at atomic weights lower than the most abundant stable isotope, 158Gd, is electron capture, and the primary mode at higher atomic weights is beta decay. The primary decay products for isotopes of weights lower than 158Gd are the element Eu (europium) isotopes and the primary products at higher weights are the element Tb (terbium) isotopes.

Gadolinium-153 has a half-life of 240.4 ±10 days and emits gamma radiation with strong peaks at 41keV and 102keV. It is used as a gamma ray source in x-ray absorptiometry or bone density gauges for osteoporosis screening, and in the Lixiscope portable x-ray imaging system.
Standard atomic mass: 157.25(3) u

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)
excitation energy
134Gd 64 70 133.95537(43)# 0.4# s 0+
135Gd 64 71 134.95257(54)# 1.1(2) s 3/2-
136Gd 64 72 135.94734(43)# 1# s [>200 ns]
137Gd 64 73 136.94502(43)# 2.2(2) s 7/2+#
138Gd 64 74 137.94012(21)# 4.7(9) s 0+
138mGd 2232.7(11) keV 6(1) µs (8-)
139Gd 64 75 138.93824(21)# 5.7(3) s 9/2-#
139mGd 250(150)# keV 4.8(9) s 1/2+#
140Gd 64 76 139.93367(3) 15.8(4) s 0+
141Gd 64 77 140.932126(21) 14(4) s (1/2+)
141mGd 377.8(2) keV 24.5(5) s (11/2-)
142Gd 64 78 141.92812(3) 70.2(6) s 0+
143Gd 64 79 142.92675(22) 39(2) s (1/2)+
143mGd 152.6(5) keV 110.0(14) s (11/2-)
144Gd 64 80 143.92296(3) 4.47(6) min 0+
145Gd 64 81 144.921709(20) 23.0(4) min 1/2+
145mGd 749.1(2) keV 85(3) s 11/2-
146Gd 64 82 145.918311(5) 48.27(10) d 0+
147Gd 64 83 146.919094(3) 38.06(12) h 7/2-
147mGd 8587.8(4) keV 510(20) ns (49/2+)
148Gd 64 84 147.918115(3) 74.6(30) a 0+
149Gd 64 85 148.919341(4) 9.28(10) d 7/2-
150Gd 64 86 149.918659(7) 1.79(8)E+6 a 0+
151Gd 64 87 150.920348(4) 124(1) d 7/2-
152Gd 64 88 151.9197910(27) 1.08(8)E+14 a 0+ 0.0020(1)
153Gd 64 89 152.9217495(27) 240.4(10) d 3/2-
153m1Gd 95.1737(12) keV 3.5(4) µs (9/2+)
153m2Gd 171.189(5) keV 76.0(14) µs (11/2-)
154Gd 64 90 153.9208656(27) STABLE 0+ 0.0218(3)
155Gd 64 91 154.9226220(27) STABLE 3/2- 0.1480(12)
155mGd 121.05(19) keV 31.97(27) ms 11/2-
156Gd 64 92 155.9221227(27) STABLE 0+ 0.2047(9)
156mGd 2137.60(5) keV 1.3(1) µs 7-
157Gd 64 93 156.9239601(27) STABLE 3/2- 0.1565(2)
158Gd 64 94 157.9241039(27) STABLE 0+ 0.2484(7)
159Gd 64 95 158.9263887(27) 18.479(4) h 3/2-
160Gd 64 96 159.9270541(27) STABLE [>31E+18 a] 0+ 0.2186(19)
161Gd 64 97 160.9296692(29) 3.646(3) min 5/2-
162Gd 64 98 161.930985(5) 8.4(2) min 0+
163Gd 64 99 162.93399(32)# 68(3) s 7/2+#
164Gd 64 100 163.93586(43)# 45(3) s 0+
165Gd 64 101 164.93938(54)# 10.3(16) s 1/2-#
166Gd 64 102 165.94160(64)# 4.8(10) s 0+
167Gd 64 103 166.94557(64)# 3# s 5/2-#
168Gd 64 104 167.94836(75)# 300# ms 0+
169Gd 64 105 168.95287(86)# 1# s 7/2-#

Notes

  • Geologically exceptional samples are known in which the isotopic composition lies outside the reported range. The uncertainty in the atomic mass may exceed the stated value for such specimens.
  • 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

  • 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.


Isotopes of europium Isotopes of gadolinium Isotopes of terbium
Index to isotope pages
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Isotopes_of_gadolinium". A list of authors is available in Wikipedia.
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