# Isotopes of germanium

Germanium ($_{32}$Ge) has five naturally occurring isotopes, $^{70}$Ge, $^{72}$Ge, $^{73}$Ge, $^{74}$Ge, and $^{76}$Ge. Of these, $^{76}$Ge is very slightly radioactive, decaying by double beta decay with a half-life of 1.78 × 10$^{21}$ years (130 billion times the age of the universe).
Stable $^{74}$Ge is the most common isotope, having a natural abundance of approximately 36%. $^{76}$Ge is the least common with a natural abundance of approximately 7%.
At least 27 radioisotopes have also been synthesized ranging in atomic mass from 58 to 89. The most stable of these is $^{68}$Ge, decaying by electron capture with a half-life of 270.95 d. It decays to the medically useful positron-emitting isotope $^{68}$Ga. (See gallium-68 generator for notes on the source of this isotope, and its medical use.) The least stable known germanium isotope is $^{59}$Ge with a half-life of 13.3 ms.
While most of germanium's radioisotopes decay by beta decay, $^{61}$Ge and $^{65}$Ge can also decay by β$^+$-delayed proton emission. $^{84}$Ge through $^{87}$Ge also have minor β$^−$-delayed neutron emission decay paths.
$^{76}$Ge is used in experiments on the nature of neutrinos, by searching for neutrinoless double beta decay.

## List of isotopes

| Nuclide | Z | N | Isotopic mass (Da) | Half-life | Decay mode | Daughter isotope | Spin and parity | Natural abundance (mole fraction) | Natural abundance (mole fraction) |
| Nuclide | Excitation energy | Excitation energy | Excitation energy | Half-life | Decay mode | Daughter isotope | Spin and parity | Normal proportion | Range of variation |
| $^{59}$Ge | 32 | 27 | 58.98243(43)# | 13.3(17) ms | β$^+$, p (93%) | $^{58}$Zn | 7/2−# | | |
| $^{59}$Ge | 32 | 27 | 58.98243(43)# | 13.3(17) ms | β$^+$ (7%) | $^{59}$Ga | 7/2−# | | |
| $^{59}$Ge | 32 | 27 | 58.98243(43)# | 13.3(17) ms | 2p (<0.2%) | $^{57}$Zn | 7/2−# | | |
| $^{60}$Ge | 32 | 28 | 59.97045(32)# | 21(6) ms | β$^+$, p | $^{59}$Zn | 0+ | | |
| $^{60}$Ge | 32 | 28 | 59.97045(32)# | 21(6) ms | β$^+$, 2p (<14%) | $^{58}$Cu | 0+ | | |
| $^{61}$Ge | 32 | 29 | 60.96373(32)# | 40.7(4) ms | β$^+$, p (87%) | $^{60}$Zn | 3/2−# | | |
| $^{61}$Ge | 32 | 29 | 60.96373(32)# | 40.7(4) ms | β$^+$ (18%) | $^{61}$Ga | 3/2−# | | |
| $^{62}$Ge | 32 | 30 | 61.95476(15)# | 82.5(14) ms | β$^+$ | $^{62}$Ga | 0+ | | |
| $^{63}$Ge | 32 | 31 | 62.949628(40) | 153.6(11) ms | β$^+$ | $^{63}$Ga | 3/2−# | | |
| $^{64}$Ge | 32 | 32 | 63.9416899(40) | 63.7(25) s | β$^+$ | $^{64}$Ga | 0+ | | |
| $^{65}$Ge | 32 | 33 | 64.9393681(23) | 30.9(5) s | β$^+$ (99.99%) | $^{65}$Ga | 3/2− | | |
| $^{65}$Ge | 32 | 33 | 64.9393681(23) | 30.9(5) s | β$^+$, p (0.011%) | $^{64}$Zn | 3/2− | | |
| $^{66}$Ge | 32 | 34 | 65.9338621(26) | 2.26(5) h | β$^+$ | $^{66}$Ga | 0+ | | |
| $^{67}$Ge | 32 | 35 | 66.9327170(46) | 18.9(3) min | β$^+$ | $^{67}$Ga | 1/2− | | |
| $^{67m1}$Ge | 18.20(5) keV | 18.20(5) keV | 18.20(5) keV | 13.7(9) μs | IT | $^{67}$Ge | 5/2− | | |
| $^{67m2}$Ge | 751.70(6) keV | 751.70(6) keV | 751.70(6) keV | 109.1(38) ns | IT | $^{67}$Ge | 9/2+ | | |
| $^{68}$Ge | 32 | 36 | 67.9280953(20) | 271.05(8) d | EC | $^{68}$Ga | 0+ | | |
| $^{69}$Ge | 32 | 37 | 68.9279645(14) | 39.05(10) h | β$^+$ | $^{69}$Ga | 5/2− | | |
| $^{69m1}$Ge | 86.76(2) keV | 86.76(2) keV | 86.76(2) keV | 5.1(2) μs | IT | $^{69}$Ge | 1/2− | | |
| $^{69m2}$Ge | 397.94(2) keV | 397.94(2) keV | 397.94(2) keV | 2.81(5) μs | IT | $^{69}$Ge | 9/2+ | | |
| $^{70}$Ge | 32 | 38 | 69.92424854(88) | Stable | Stable | Stable | 0+ | 0.2052(19) | |
| $^{71}$Ge | 32 | 39 | 70.92495212(87) | 11.468(8) d | EC | $^{71}$Ga | 1/2− | | |
| $^{71m}$Ge | 198.354(14) keV | 198.354(14) keV | 198.354(14) keV | 20.41(18) ms | IT | $^{71}$Ge | 9/2+ | | |
| $^{72}$Ge | 32 | 40 | 71.922075824(81) | Stable | Stable | Stable | 0+ | 0.2745(15) | |
| $^{72m}$Ge | 691.43(4) keV | 691.43(4) keV | 691.43(4) keV | 444.2(8) ns | IT | $^{72}$Ge | 0+ | | |
| $^{73}$Ge | 32 | 41 | 72.923458954(61) | Stable | Stable | Stable | 9/2+ | 0.0776(8) | |
| $^{73m1}$Ge | 13.2845(15) keV | 13.2845(15) keV | 13.2845(15) keV | 2.91(3) μs | IT | $^{73}$Ge | 5/2+ | | |
| $^{73m2}$Ge | 66.725(9) keV | 66.725(9) keV | 66.725(9) keV | 499(11) ms | IT | $^{73}$Ge | 1/2− | | |
| $^{74}$Ge | 32 | 42 | 73.921177760(13) | Stable | Stable | Stable | 0+ | 0.3652(12) | |
| $^{75}$Ge | 32 | 43 | 74.922858370(55) | 82.78(4) min | β$^−$ | $^{75}$As | 1/2− | | |
| $^{75m1}$Ge | 139.69(3) keV | 139.69(3) keV | 139.69(3) keV | 47.7(5) s | IT (99.97%) | $^{75}$Ge | 7/2+ | | |
| $^{75m1}$Ge | 139.69(3) keV | 139.69(3) keV | 139.69(3) keV | 47.7(5) s | β$^−$ (0.030%) | $^{75}$As | 7/2+ | | |
| $^{75m2}$Ge | 192.19(6) keV | 192.19(6) keV | 192.19(6) keV | 216(5) ns | IT | $^{75}$Ge | 5/2+ | | |
| $^{76}$Ge | 32 | 44 | 75.921402725(19) | (2.022±0.018±0.038)×10$^{21}$ y | β$^−$β$^−$ | $^{76}$Se | 0+ | 0.0775(12) | |
| $^{77}$Ge | 32 | 45 | 76.923549843(56) | 11.211(3) h | β$^−$ | $^{77}$As | 7/2+ | | |
| $^{77m}$Ge | 159.71(6) keV | 159.71(6) keV | 159.71(6) keV | 53.7(6) s | β$^−$ (81%) | $^{77}$As | 1/2− | | |
| $^{77m}$Ge | 159.71(6) keV | 159.71(6) keV | 159.71(6) keV | 53.7(6) s | IT (19%) | $^{77}$Ge | 1/2− | | |
| $^{78}$Ge | 32 | 46 | 77.9228529(38) | 88.0(10) min | β$^−$ | $^{78}$As | 0+ | | |
| $^{79}$Ge | 32 | 47 | 78.925360(40) | 18.98(3) s | β$^−$ | $^{79}$As | (1/2)− | | |
| $^{79m}$Ge | 185.95(4) keV | 185.95(4) keV | 185.95(4) keV | 39.0(10) s | β$^−$ (96%) | $^{79}$As | 7/2+# | | |
| $^{79m}$Ge | 185.95(4) keV | 185.95(4) keV | 185.95(4) keV | 39.0(10) s | IT (4%) | $^{79}$Ge | 7/2+# | | |
| $^{80}$Ge | 32 | 48 | 79.9253508(22) | 29.5(4) s | β$^−$ | $^{80}$As | 0+ | | |
| $^{81}$Ge | 32 | 49 | 80.9288329(22) | 9(2) s | β$^−$ | $^{81}$As | 9/2+# | | |
| $^{81m}$Ge | 679.14(4) keV | 679.14(4) keV | 679.14(4) keV | 6(2) s | β$^−$ | $^{81}$As | (1/2+) | | |
| $^{81m}$Ge | 679.14(4) keV | 679.14(4) keV | 679.14(4) keV | 6(2) s | IT (<1%) | $^{81}$Ge | (1/2+) | | |
| $^{82}$Ge | 32 | 50 | 81.9297740(24) | 4.31(19) s | β$^−$ | $^{82}$As | 0+ | | |
| $^{83}$Ge | 32 | 51 | 82.9345391(26) | 1.85(6) s | β$^−$ | $^{83}$As | (5/2+) | | |
| $^{84}$Ge | 32 | 52 | 83.9375751(34) | 951(9) ms | β$^−$ (89.4%) | $^{84}$As | 0+ | | |
| $^{84}$Ge | 32 | 52 | 83.9375751(34) | 951(9) ms | β$^−$, n (10.6%) | $^{83}$As | 0+ | | |
| $^{85}$Ge | 32 | 53 | 84.9429697(40) | 495(5) ms | β$^−$ (82.8%) | $^{85}$As | (3/2+,5/2+)# | | |
| $^{85}$Ge | 32 | 53 | 84.9429697(40) | 495(5) ms | β$^−$, n (17.2%) | $^{84}$As | (3/2+,5/2+)# | | |
| $^{86}$Ge | 32 | 54 | 85.94697(47) | 221.6(11) ms | β$^−$ (55%) | $^{86}$As | 0+ | | |
| $^{86}$Ge | 32 | 54 | 85.94697(47) | 221.6(11) ms | β$^−$, n (45%) | $^{85}$As | 0+ | | |
| $^{87}$Ge | 32 | 55 | 86.95320(32)# | 103(4) ms | β$^−$ | $^{87}$As | 5/2+# | | |
| $^{88}$Ge | 32 | 56 | 87.95757(43)# | 61(6) ms | β$^−$ | $^{88}$As | 0+ | | |
| $^{89}$Ge | 32 | 57 | 88.96453(43)# | 60# ms [>300 ns] | | | 3/2+# | | |
| $^{90}$Ge | 32 | 58 | 89.96944(54)# | 30# ms [>400 ns] | | | 0+ | | |
| $^{91}$Ge | 32 | 59 | | | | | | | |
| $^{92}$Ge | 32 | 60 | | | | | | | |
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* ↑ $^m$Ge – Excited nuclear isomer.
* ↑ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
* ↑ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
* ↑ Bold half-life – nearly stable, half-life longer than age of universe.
* 1 2 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
* ↑ Modes of decay: EC:Electron capture IT:Isomeric transition n:Neutron emission p:Proton emission
* ↑ Bold symbol as daughter – Daughter product is stable.
* ↑ ( ) spin value – Indicates spin with weak assignment arguments.
* ↑ Used to generate $^{68}$Ga
* ↑ Primordial radionuclide