Isotopes of germanium

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Main isotopes of germanium (32Ge)
Iso­tope Decay
abun­dance half-life (t1/2) mode pro­duct
68Ge syn 270.8 d ε 68Ga
70Ge 20.52% stable
71Ge syn 11.3 d ε 71Ga
72Ge 27.45% stable
73Ge 7.76% stable
74Ge 36.52% stable
76Ge 7.75% 1.78×1021 y ββ 76Se
Standard atomic weight Ar, standard(Ge)

Germanium (32Ge) has five naturally occurring isotopes, 70Ge, 72Ge, 73Ge, 74Ge, and 76Ge. Of these, 76Ge is very slightly radioactive, decaying by double beta decay with a half-life of 1.78 × 1021 years[2] (130 billion times the age of the universe).

Stable 74Ge is the most common isotope, having a natural abundance of approximately 36%. 76Ge is the least common with a natural abundance of approximately 7%.[3] When bombarded with alpha particles, the isotopes 72Ge and 76Ge will generate stable 75As and 77Se, releasing high energy electrons in the process.[4]

At least 27 radioisotopes have also been synthesized ranging in atomic mass from 58 to 89. The most stable of these is 68Ge, decaying by electron capture with a half-life of 270.95 d. It decays to the medically useful positron-emitting isotope 68Ga. (See gallium-68 generator for notes on the source of this isotope, and its medical use). The least stable known germanium isotope is 60Ge with a half-life of 30 ms.

While most of germanium's radioisotopes decay by beta decay, 61Ge and 64Ge decay by β+ delayed proton emission.[3] 84Ge through 87Ge also have minor β delayed neutron emission decay paths.[3]

76Ge is used in experiments on the nature of neutrinos, by searching for neutrinoless double beta decay.

List of isotopes[edit]

Nuclide
[n 1]
Z N Isotopic mass (u)
[n 2][n 3]
Half-life
[n 4][n 5]
Decay
mode

[n 6]
Daughter
isotope

[n 7]
Spin and
parity
[n 8][n 5]
Natural abundance (mole fraction)
Excitation energy Normal proportion Range of variation
58Ge 32 26 57.99101(34)# 2p 56Zn 0+
59Ge 32 27 58.98175(30)# 2p 57Zn 7/2−#
60Ge 32 28 59.97019(25)# 30# ms β+ 60Ga 0+
2p 58Zn
61Ge 32 29 60.96379(32)# 39(12) ms β+, p (80%) 60Zn (3/2−)#
β+ (20%) 61Ga
62Ge 32 30 61.95465(15)# 129(35) ms β+ 62Ga 0+
63Ge 32 31 62.94964(21)# 142(8) ms β+ 63Ga (3/2−)#
64Ge 32 32 63.94165(3) 63.7(25) s β+ 64Ga 0+
65Ge 32 33 64.93944(11) 30.9(5) s β+ (99.99%) 65Ga (3/2)−
β+, p (.01%) 64Zn
66Ge 32 34 65.93384(3) 2.26(5) h β+ 66Ga 0+
67Ge 32 35 66.932734(5) 18.9(3) min β+ 67Ga 1/2−
67m1Ge 18.20(5) keV 13.7(9) μs 5/2−
67m2Ge 751.70(6) keV 110.9(14) ns 9/2+
68Ge[n 9] 32 36 67.928094(7) 270.95(16) d[5] EC 68Ga 0+
69Ge 32 37 68.9279645(14) 39.05(10) h β+ 69Ga 5/2−
69m1Ge 86.765(14) keV 5.1(2) μs 1/2−
69m2Ge 397.944(18) keV 2.81(5) μs 9/2+
70Ge 32 38 69.9242474(11) Stable 0+ 0.2038(18)
71Ge 32 39 70.9249510(11) 11.43(3) d EC 71Ga 1/2−
71mGe 198.367(10) keV 20.40(17) ms IT 71Ge 9/2+
72Ge 32 40 71.9220758(18) Stable 0+ 0.2731(26)
72mGe 691.43(4) keV 444.2(8) ns 0+
73Ge 32 41 72.9234589(18) Stable 9/2+ 0.0776(8)
73m1Ge 13.2845(15) keV 2.92(3) μs 5/2+
73m2Ge 66.726(9) keV 499(11) ms 1/2−
74Ge 32 42 73.9211778(18) Stable 0+ 0.3672(15)
75Ge 32 43 74.9228589(18) 82.78(4) min β 75As 1/2−
75m1Ge 139.69(3) keV 47.7(5) s IT (99.97%) 75Ge 7/2+
β 75As
75m2Ge 192.18(7) keV 216(5) ns 5/2+
76Ge[n 10] 32 44 75.9214026(18) 1.926(94)×1021 y[6] ββ 76Se 0+ 0.0783(7)
77Ge 32 45 76.9235486(18) 11.30(1) h β 77As 7/2+
77mGe 159.70(10) keV 52.9(6) s β (79%) 77As 1/2−
IT (21%) 77Ge
78Ge 32 46 77.922853(4) 88(1) min β 78As 0+
79Ge 32 47 78.9254(1) 18.98(3) s β 79As (1/2)−
79mGe 185.95(4) keV 39.0(10) s β (96%) 79As (7/2+)#
IT (4%) 79Ge
80Ge 32 48 79.92537(3) 29.5(4) s β 80As 0+
81Ge 32 49 80.92882(13) 7.6(6) s β 81As 9/2+#
81mGe 679.13(4) keV 7.6(6) s β (99%) 81As (1/2+)
IT (1%) 81Ge
82Ge 32 50 81.92955(26) 4.55(5) s β 82As 0+
83Ge 32 51 82.93462(21)# 1.85(6) s β 83As (5/2+)#
84Ge 32 52 83.93747(32)# 0.947(11) s β (89.2%) 84As 0+
β, n (10.8%) 83As
85Ge 32 53 84.94303(43)# 535(47) ms β (86%) 85As 5/2+#
β, n (14%) 84As
86Ge 32 54 85.94649(54)# >150 ns β, n 85As 0+
β 86As
87Ge 32 55 86.95251(54)# 0.14# s 5/2+#
88Ge 32 56 87.95691(75)# >=300 ns 0+
89Ge 32 57 88.96383(97)# >150 ns 3/2+#
  1. ^ mGe – Excited nuclear isomer.
  2. ^ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  3. ^ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
  4. ^ Bold half-life – nearly stable, half-life longer than age of universe.
  5. ^ a b # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  6. ^ Modes of decay:
    EC: Electron capture
    IT: Isomeric transition
    n: Neutron emission
    p: Proton emission
  7. ^ Bold symbol as daughter – Daughter product is stable.
  8. ^ ( ) spin value – Indicates spin with weak assignment arguments.
  9. ^ Used to generate 68Ga
  10. ^ Primordial radionuclide
  • Angular momentum or 3rd order sub particles are omitted as spin(2)=0,45,45.

References[edit]

  • Isotope masses from:
    • Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
  • Isotopic compositions and standard atomic masses from:
  • Half-life, spin, and isomer data selected from the following sources.
  1. ^ Meija, Juris; et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry. 88 (3): 265–91. doi:10.1515/pac-2015-0305.
  2. ^ A. M. Bakalyarov; A. Ya. Balysh; S. T. Belyaev; V. I. Lebedev; S. V. Zhukov (2003). "Results of the experiment on investigation of Germanium-76 double beta decay". Physics of Particles and Nuclei Letters. 2 (2): 77–81. arXiv:hep-ex/0309016. Bibcode:2003hep.ex....9016B.
  3. ^ a b c Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
  4. ^ Via a set of two reactions:
    4He + 72Ge → 75Se + 1n, 75Se decays by electron capture to 75As with a half-life of 120 days
    76Ge + 1n → 77Ge, which then undergoes beta decay to 77As with a half-life of 11.3 hours, which in turn undergoes beta decay to 77Se with a half-life of 39 hours
  5. ^ [1]
  6. ^ Patrignani, C.; et al. (Particle Data Group) (2016). "Review of Particle Physics". Chinese Physics C. 40 (10): 100001. Bibcode:2016ChPhC..40j0001P. doi:10.1088/1674-1137/40/10/100001. See p. 768