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.
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