Isotopes of gadolinium

From Wikipedia, the free encyclopedia
  (Redirected from Gadolinium-156)
Jump to: navigation, search

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 (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 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[edit]

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)
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] β+ 136Eu
137Gd 64 73 136.94502(43)# 2.2(2) s β+ 137Eu 7/2+#
β+, p (rare) 136Sm
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-#
β+, p (rare) 138Sm
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+)
β+, p (.03%) 140Sm
141mGd 377.8(2) keV 24.5(5) s β+ (89%) 141Eu (11/2-)
IT (11%) 141Gd
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-
β+ (5.7%) 145Eu
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+
β+β+ (rare) 148Sm
149Gd 64 85 148.919341(4) 9.28(10) d β+ 149Eu 7/2-
α (4.34×10−4%) 145Sm
150Gd 64 86 149.918659(7) 1.79(8)×106 a α 146Sm 0+
β+β+ (rare) 150Sm
151Gd 64 87 150.920348(4) 124(1) d EC 151Eu 7/2-
α (10−6%) 147Sm
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-#
  1. ^ Bold for isotopes with half-lives longer than the age of the universe (nearly stable)
  2. ^ Abbreviations:
    EC: Electron capture
    IT: Isomeric transition
  3. ^ Bold for stable isotopes, bold italics for nearly-stable isotopes (half-life longer than the age of the universe)
  4. ^ primordial radionuclide
  5. ^ Believed to undergo α decay to 150Sm
  6. ^ a b c d e f Fission product
  7. ^ Believed to undergo α decay to 151Sm
  8. ^ a b c Theoretically capable of spontaneous fission
  9. ^ Believed to undergo β-β- decay to 160Dy with a half-life over 1.3×1021 years

Notes[edit]

  • 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[edit]

  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. 
  2. ^ "Universal Nuclide Chart". Nucleonica. Retrieved 2012-05-30. 


Isotopes of europium Isotopes of gadolinium Isotopes of terbium
Table of nuclides