Isotopes of gadolinium

Naturally occurring gadolinium (Gd) is composed of 6 stable isotopes, ¹⁵⁴Gd, ¹⁵⁵Gd, ¹⁵⁶Gd, ¹⁵⁷Gd, ¹⁵⁸Gd and ¹⁶⁰Gd, and 1 radioisotope, ¹⁵²Gd, with ¹⁵⁸Gd being the most abundant (24.84% natural abundance). The predicted double beta decay of ¹⁶⁰Gd has never been observed; only lower limit on its half-life of more than 1.3×10²¹ years has been set experimentally.^[1]

Thirty radioisotopes have been characterized, with the most stable being alpha-decaying ¹⁵²Gd (naturally occurring) with a half-life of 1.08×10¹⁴ years, and ¹⁵⁰Gd with a half-life of 1.79×10⁶ years. All of the remaining radioactive isotopes have half-lives less than 74.7 years. The majority of these have half-lives less than 24.6 seconds. Gadolinium isotopes have 10 metastable isomers, with the most stable being ^143mGd (t_1/2=110 seconds), ^145mGd (t_1/2=85 seconds) and ^141mGd (t_1/2=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 41 keV and 102 keV. 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^{[n 1]}	decay mode(s)^[2]^{[n 2]}	daughter isotope(s)^{[n 3]}	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
nuclide symbol	excitation energy			half-life^{[n 1]}	decay mode(s)^[2]^{[n 2]}	daughter isotope(s)^{[n 3]}	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
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]	β⁺	¹³⁶Eu
¹³⁷Gd	64	73	136.94502(43)#	2.2(2) s	β⁺	¹³⁷Eu	7/2+#
¹³⁷Gd	64	73	136.94502(43)#	2.2(2) s	β⁺, p (rare)	¹³⁶Sm	7/2+#
¹³⁸Gd	64	74	137.94012(21)#	4.7(9) s	β⁺	¹³⁸Eu	0+
^138mGd	2232.7(11) keV			6(1) µs			(8-)
¹³⁹Gd	64	75	138.93824(21)#	5.7(3) s	β⁺	¹³⁹Eu	9/2-#
¹³⁹Gd	64	75	138.93824(21)#	5.7(3) s	β⁺, p (rare)	¹³⁸Sm	9/2-#
^139mGd	250(150)# keV			4.8(9) s			1/2+#
¹⁴⁰Gd	64	76	139.93367(3)	15.8(4) s	β⁺	¹⁴⁰Eu	0+
¹⁴¹Gd	64	77	140.932126(21)	14(4) s	β⁺ (99.97%)	¹⁴¹Eu	(1/2+)
¹⁴¹Gd	64	77	140.932126(21)	14(4) s	β⁺, p (.03%)	¹⁴⁰Sm	(1/2+)
^141mGd	377.8(2) keV			24.5(5) s	β⁺ (89%)	¹⁴¹Eu	(11/2-)
^141mGd	377.8(2) keV			24.5(5) s	IT (11%)	¹⁴¹Gd	(11/2-)
¹⁴²Gd	64	78	141.92812(3)	70.2(6) s	β⁺	¹⁴²Eu	0+
¹⁴³Gd	64	79	142.92675(22)	39(2) s	β⁺	¹⁴³Eu	(1/2)+
					β⁺, α (rare)	¹³⁹Pm
					β⁺, p (rare)	¹⁴²Sm
^143mGd	152.6(5) keV			110.0(14) s	β⁺	¹⁴³Eu	(11/2-)
					β⁺, α (rare)	¹³⁹Pm
					β⁺, p (rare)	¹⁴²Sm
¹⁴⁴Gd	64	80	143.92296(3)	4.47(6) min	β⁺	¹⁴⁴Eu	0+
¹⁴⁵Gd	64	81	144.921709(20)	23.0(4) min	β⁺	¹⁴⁵Eu	1/2+
^145mGd	749.1(2) keV			85(3) s	IT (94.3%)	¹⁴⁵Gd	11/2-
^145mGd	749.1(2) keV			85(3) s	β⁺ (5.7%)	¹⁴⁵Eu	11/2-
¹⁴⁶Gd	64	82	145.918311(5)	48.27(10) d	EC	¹⁴⁶Eu	0+
¹⁴⁷Gd	64	83	146.919094(3)	38.06(12) h	β⁺	¹⁴⁷Eu	7/2-
^147mGd	8587.8(4) keV			510(20) ns			(49/2+)
¹⁴⁸Gd	64	84	147.918115(3)	74.6(30) a	α	¹⁴⁴Sm	0+
¹⁴⁸Gd	64	84	147.918115(3)	74.6(30) a	β⁺β⁺ (rare)	¹⁴⁸Sm	0+
¹⁴⁹Gd	64	85	148.919341(4)	9.28(10) d	β⁺	¹⁴⁹Eu	7/2-
¹⁴⁹Gd	64	85	148.919341(4)	9.28(10) d	α (4.34×10⁻⁴%)	¹⁴⁵Sm	7/2-
¹⁵⁰Gd	64	86	149.918659(7)	1.79(8)×10⁶ a	α	¹⁴⁶Sm	0+
¹⁵⁰Gd	64	86	149.918659(7)	1.79(8)×10⁶ a	β⁺β⁺ (rare)	¹⁵⁰Sm	0+
¹⁵¹Gd	64	87	150.920348(4)	124(1) d	EC	¹⁵¹Eu	7/2-
¹⁵¹Gd	64	87	150.920348(4)	124(1) d	α (10⁻⁶%)	¹⁴⁷Sm	7/2-
¹⁵²Gd^{[n 4]}	64	88	151.9197910(27)	1.08(8)×10¹⁴ a	α	¹⁴⁸Sm	0+	0.0020(1)
¹⁵³Gd	64	89	152.9217495(27)	240.4(10) d	EC	¹⁵³Eu	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)	Observationally Stable^{[n 5]}			0+	0.0218(3)
¹⁵⁵Gd^{[n 6]}	64	91	154.9226220(27)	Observationally Stable^{[n 7]}			3/2-	0.1480(12)
^155mGd	121.05(19) keV			31.97(27) ms	IT	¹⁵⁵Gd	11/2-
¹⁵⁶Gd^{[n 6]}	64	92	155.9221227(27)	Stable^{[n 8]}			0+	0.2047(9)
^156mGd	2137.60(5) keV			1.3(1) µs			7-
¹⁵⁷Gd^{[n 6]}	64	93	156.9239601(27)	Stable^{[n 8]}			3/2-	0.1565(2)
¹⁵⁸Gd^{[n 6]}	64	94	157.9241039(27)	Stable^{[n 8]}			0+	0.2484(7)
¹⁵⁹Gd^{[n 6]}	64	95	158.9263887(27)	18.479(4) h	β^-	¹⁵⁹Tb	3/2-
¹⁶⁰Gd^{[n 6]}	64	96	159.9270541(27)	Observationally Stable^{[n 9]}			0+	0.2186(19)
¹⁶¹Gd	64	97	160.9296692(29)	3.646(3) min	β^-	¹⁶¹Tb	5/2-
¹⁶²Gd	64	98	161.930985(5)	8.4(2) min	β^-	¹⁶²Tb	0+
¹⁶³Gd	64	99	162.93399(32)#	68(3) s	β^-	¹⁶³Tb	7/2+#
¹⁶⁴Gd	64	100	163.93586(43)#	45(3) s	β^-	¹⁶⁴Tb	0+
¹⁶⁵Gd	64	101	164.93938(54)#	10.3(16) s	β^-	¹⁶⁵Tb	1/2-#
¹⁶⁶Gd	64	102	165.94160(64)#	4.8(10) s	β^-	¹⁶⁶Tb	0+
¹⁶⁷Gd	64	103	166.94557(64)#	3# s	β^-	¹⁶⁷Tb	5/2-#
¹⁶⁸Gd	64	104	167.94836(75)#	300# ms	β^-	¹⁶⁸Tb	0+
¹⁶⁹Gd	64	105	168.95287(86)#	1# s	β^-	¹⁶⁹Tb	7/2-#

^ Bold for isotopes with half-lives longer than the age of the universe (nearly stable)
^ Abbreviations:
EC: Electron capture
IT: Isomeric transition
^ Bold for stable isotopes, bold italics for nearly-stable isotopes (half-life longer than the age of the universe)
^ primordial radionuclide
^ Believed to undergo α decay to ¹⁵⁰Sm
^ ^a ^b ^c ^d ^e ^f Fission product
^ Believed to undergo α decay to ¹⁵¹Sm
^ ^a ^b ^c Theoretically capable of spontaneous fission
^ Believed to undergo β^-β^- decay to ¹⁶⁰Dy with a half-life over 1.3×10²¹ years

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

^ F. A. Danevich; et al. (2001). "Quest for double beta decay of ¹⁶⁰Gd and Ce isotopes". Nuclear Physics A. 694: 375. arXiv:nucl-ex/0011020. Bibcode:2001NuPhA.694..375D. doi:10.1016/S0375-9474(01)00983-6. {{cite journal}}: Explicit use of et al. in: |author= (help)
^ "Universal Nuclide Chart". Nucleonica. Retrieved 2012-05-30.

Isotope masses from:
- G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and 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.{{cite journal}}: CS1 maint: multiple names: authors list (link)
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 and 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.{{cite journal}}: CS1 maint: multiple names: authors list (link)
- 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. {{cite journal}}: Unknown parameter |laysummary= ignored (help)
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 and 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.{{cite journal}}: CS1 maint: multiple names: authors list (link)
- National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. Retrieved September 2005. {{cite web}}: Check date values in: |accessdate= (help)
- N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide (ed.). CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0-8493-0485-9. {{cite book}}: Unknown parameter |nopp= ignored (|no-pp= suggested) (help)

[2] Bold for isotopes with half-lives longer than the age of the universe (nearly stable)

[4] Abbreviations:
EC: Electron capture
IT: Isomeric transition

[5] Bold for stable isotopes, bold italics for nearly-stable isotopes (half-life longer than the age of the universe)

[6] rimordial radionuclide

[7] Believed to undergo α decay to ¹⁵⁰Sm

[FP-8] ^ ^a ^b ^c ^d ^e ^f Fission product

[9] Believed to undergo α decay to ¹⁵¹Sm

[SF-10] Theoretically capable of spontaneous fission

[11] Believed to undergo β^-β^- decay to ¹⁶⁰Dy with a half-life over 1.3×10²¹ years

[DBD-1] F. A. Danevich; et al. (2001). "Quest for double beta decay of ¹⁶⁰Gd and Ce isotopes". Nuclear Physics A. 694: 375. arXiv:nucl-ex/0011020. Bibcode:2001NuPhA.694..375D. doi:10.1016/S0375-9474(01)00983-6. {{cite journal}}: Explicit use of et al. in: |author= (help)

[3] "Universal Nuclide Chart". Nucleonica. Retrieved 2012-05-30.

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