Germanium Germanium is a chemical element with the symbol Ge and atomic number 32. It is lustrous, hard-brittle, grayish-white and similar in appearance to silicon. It is a metalloid in the carbon group that is chemically similar to its group neighbors s ...

(₃₂Ge) has five naturally occurring

isotope Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbers) ...

s, ⁷⁰Ge, ⁷²Ge, ⁷³Ge, ⁷⁴Ge, and ⁷⁶Ge. Of these, ⁷⁶Ge is very slightly radioactive, decaying by

double beta decay In nuclear physics, double beta decay is a type of radioactive decay in which two neutrons are simultaneously transformed into two protons, or vice versa, inside an atomic nucleus. As in single beta decay, this process allows the atom to move clos ...

with a

half-life Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable ato ...

of 1.78 × 10²¹ years (130 billion times the

age of the universe In physical cosmology, the age of the universe is the time elapsed since the Big Bang. Astronomers have derived two different measurements of the age of the universe: a measurement based on direct observations of an early state of the universe, ...

). Stable ⁷⁴Ge is the most common isotope, having a

natural abundance In physics, natural abundance (NA) refers to the abundance of isotopes of a chemical element as naturally found on a planet. The relative atomic mass (a weighted average, weighted by mole-fraction abundance figures) of these isotopes is the atomic ...

of approximately 36%. ⁷⁶Ge is the least common with a natural abundance of approximately 7%. When bombarded with alpha particles, the isotopes ⁷²Ge and ⁷⁶Ge will generate stable ⁷⁵As and ⁷⁷Se, releasing high energy electrons in the process.Via a set of two reactions:
⁴He + ⁷²Ge → ⁷⁵Se + ¹n, ⁷⁵Se decays by

electron capture Electron capture (K-electron capture, also K-capture, or L-electron capture, L-capture) is a process in which the proton-rich nucleus of an electrically neutral atom absorbs an inner atomic electron, usually from the K or L electron shells. Thi ...

to ⁷⁵As with a half-life of 120 days
⁷⁶Ge + ¹n → ⁷⁷Ge, which then undergoes

beta decay In nuclear physics, beta decay (β-decay) is a type of radioactive decay in which a beta particle (fast energetic electron or positron) is emitted from an atomic nucleus, transforming the original nuclide to an isobar of that nuclide. For ...

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 At least 27

radioisotope A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transferr ...

s have also been synthesized ranging in atomic mass from 58 to 89. The most stable of these is ⁶⁸Ge, decaying by

with a half-life of 270.95 d. It decays to the medically useful positron-emitting isotope ⁶⁸Ga. (See

gallium-68 generator A germanium-68/gallium-68 generator is a device used to extract the positron-emitting isotope 68Ga of gallium from a source of decaying germanium-68. The parent isotope 68Ge has a half-life of 271 days and can be easily utilized for in-hospital p ...

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

, ⁶¹Ge and ⁶⁴Ge decay by β⁺ delayed

proton emission Proton emission (also known as proton radioactivity) is a rare type of radioactive decay in which a proton is ejected from a nucleus. Proton emission can occur from high-lying excited states in a nucleus following a beta decay, in which case t ...

. ⁸⁴Ge through ⁸⁷Ge also have minor β⁻ delayed

neutron emission Neutron emission is a mode of radioactive decay in which one or more neutrons are ejected from a nucleus. It occurs in the most neutron-rich/proton-deficient nuclides, and also from excited states of other nuclides as in photoneutron emission and ...

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

neutrinoless double beta decay The neutrinoless double beta decay (0νββ) is a commonly proposed and experimentally pursued theoretical radioactive decay process that would prove a Majorana nature of the neutrino particle. To this day, it has not been found. The discovery o ...

List of isotopes

, - , ⁵⁸Ge , style="text-align:right" , 32 , style="text-align:right" , 26 , 57.99101(34)# , , 2p , ⁵⁶Zn , 0+ , , , - , ⁵⁹Ge , style="text-align:right" , 32 , style="text-align:right" , 27 , 58.98175(30)# , , 2p , ⁵⁷Zn , 7/2−# , , , - , rowspan=2, ⁶⁰Ge , rowspan=2 style="text-align:right" , 32 , rowspan=2 style="text-align:right" , 28 , rowspan=2, 59.97019(25)# , rowspan=2, 30# ms , β⁺ , ⁶⁰Ga , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , 2p , ⁵⁸Zn , - , rowspan=2, ⁶¹Ge , rowspan=2 style="text-align:right" , 32 , rowspan=2 style="text-align:right" , 29 , rowspan=2, 60.96379(32)# , rowspan=2, 39(12) ms , β⁺, p (80%) , ⁶⁰Zn , rowspan=2, (3/2−)# , rowspan=2, , rowspan=2, , - , β⁺ (20%) , ⁶¹Ga , - , ⁶²Ge , style="text-align:right" , 32 , style="text-align:right" , 30 , 61.95465(15)# , 129(35) ms , β⁺ , ⁶²Ga , 0+ , , , - , ⁶³Ge , style="text-align:right" , 32 , style="text-align:right" , 31 , 62.94964(21)# , 142(8) ms , β⁺ , ⁶³Ga , (3/2−)# , , , - , ⁶⁴Ge , style="text-align:right" , 32 , style="text-align:right" , 32 , 63.94165(3) , 63.7(25) s , β⁺ , ⁶⁴Ga , 0+ , , , - , rowspan=2, ⁶⁵Ge , rowspan=2 style="text-align:right" , 32 , rowspan=2 style="text-align:right" , 33 , rowspan=2, 64.93944(11) , rowspan=2, 30.9(5) s , β⁺ (99.99%) , ⁶⁵Ga , rowspan=2, (3/2)− , rowspan=2, , rowspan=2, , - , β⁺, p (.01%) , ⁶⁴Zn , - , ⁶⁶Ge , style="text-align:right" , 32 , style="text-align:right" , 34 , 65.93384(3) , 2.26(5) h , β⁺ , ⁶⁶Ga , 0+ , , , - , ⁶⁷Ge , style="text-align:right" , 32 , style="text-align:right" , 35 , 66.932734(5) , 18.9(3) min , β⁺ , ⁶⁷Ga , 1/2− , , , - , style="text-indent:1em" , ^67m1Ge , colspan="3" style="text-indent:2em" , 18.20(5) keV , 13.7(9) μs , , , 5/2− , , , - , style="text-indent:1em" , ^67m2Ge , colspan="3" style="text-indent:2em" , 751.70(6) keV , 110.9(14) ns , , , 9/2+ , , , - , ⁶⁸GeUsed to generate ⁶⁸Ga , style="text-align:right" , 32 , style="text-align:right" , 36 , 67.928094(7) , 271.05(8) d , EC , ⁶⁸Ga , 0+ , , , - , ⁶⁹Ge , style="text-align:right" , 32 , style="text-align:right" , 37 , 68.9279645(14) , 39.05(10) h , β⁺ , ⁶⁹Ga , 5/2− , , , - , style="text-indent:1em" , ^69m1Ge , colspan="3" style="text-indent:2em" , 86.765(14) keV , 5.1(2) μs , , , 1/2− , , , - , style="text-indent:1em" , ^69m2Ge , colspan="3" style="text-indent:2em" , 397.944(18) keV , 2.81(5) μs , , , 9/2+ , , , - , ⁷⁰Ge , style="text-align:right" , 32 , style="text-align:right" , 38 , 69.9242474(11) , colspan=3 align=center, Stable , 0+ , 0.2038(18) , , - , ⁷¹Ge , style="text-align:right" , 32 , style="text-align:right" , 39 , 70.9249510(11) , 11.43(3) d , EC , ⁷¹Ga , 1/2− , , , - , style="text-indent:1em" , ^71mGe , colspan="3" style="text-indent:2em" , 198.367(10) keV , 20.40(17) ms , IT , ⁷¹Ge , 9/2+ , , , - , ⁷²Ge , style="text-align:right" , 32 , style="text-align:right" , 40 , 71.9220758(18) , colspan=3 align=center, Stable , 0+ , 0.2731(26) , , - , style="text-indent:1em" , ^72mGe , colspan="3" style="text-indent:2em" , 691.43(4) keV , 444.2(8) ns , , , 0+ , , , - , ⁷³Ge , style="text-align:right" , 32 , style="text-align:right" , 41 , 72.9234589(18) , colspan=3 align=center, Stable , 9/2+ , 0.0776(8) , , - , style="text-indent:1em" , ^73m1Ge , colspan="3" style="text-indent:2em" , 13.2845(15) keV , 2.92(3) μs , , , 5/2+ , , , - , style="text-indent:1em" , ^73m2Ge , colspan="3" style="text-indent:2em" , 66.726(9) keV , 499(11) ms , , , 1/2− , , , - , ⁷⁴Ge , style="text-align:right" , 32 , style="text-align:right" , 42 , 73.9211778(18) , colspan=3 align=center, Stable , 0+ , 0.3672(15) , , - , ⁷⁵Ge , style="text-align:right" , 32 , style="text-align:right" , 43 , 74.9228589(18) , 82.78(4) min , β⁻ , ⁷⁵As , 1/2− , , , - , rowspan=2 style="text-indent:1em" , ^75m1Ge , rowspan=2 colspan="3" style="text-indent:2em" , 139.69(3) keV , rowspan=2, 47.7(5) s , IT (99.97%) , ⁷⁵Ge , rowspan=2, 7/2+ , rowspan=2, , rowspan=2, , - , β⁻ , ⁷⁵As , - , style="text-indent:1em" , ^75m2Ge , colspan="3" style="text-indent:2em" , 192.18(7) keV , 216(5) ns , , , 5/2+ , , , - , ⁷⁶Ge Primordial

radionuclide A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transfer ...

, style="text-align:right" , 32 , style="text-align:right" , 44 , 75.9214026(18) , See p. 768 , β⁻β⁻ , ⁷⁶Se , 0+ , 0.0783(7) , , - , ⁷⁷Ge , style="text-align:right" , 32 , style="text-align:right" , 45 , 76.9235486(18) , 11.30(1) h , β⁻ , ⁷⁷As , 7/2+ , , , - , rowspan=2 style="text-indent:1em" , ^77mGe , rowspan=2 colspan="3" style="text-indent:2em" , 159.70(10) keV , rowspan=2, 52.9(6) s , β⁻ (79%) , ⁷⁷As , rowspan=2, 1/2− , rowspan=2, , rowspan=2, , - , IT (21%) , ⁷⁷Ge , - , ⁷⁸Ge , style="text-align:right" , 32 , style="text-align:right" , 46 , 77.922853(4) , 88(1) min , β⁻ , ⁷⁸As , 0+ , , , - , ⁷⁹Ge , style="text-align:right" , 32 , style="text-align:right" , 47 , 78.9254(1) , 18.98(3) s , β⁻ , ⁷⁹As , (1/2)− , , , - , rowspan=2 style="text-indent:1em" , ^79mGe , rowspan=2 colspan="3" style="text-indent:2em" , 185.95(4) keV , rowspan=2, 39.0(10) s , β⁻ (96%) , ⁷⁹As , rowspan=2, (7/2+)# , rowspan=2, , rowspan=2, , - , IT (4%) , ⁷⁹Ge , - , ⁸⁰Ge , style="text-align:right" , 32 , style="text-align:right" , 48 , 79.92537(3) , 29.5(4) s , β⁻ , ⁸⁰As , 0+ , , , - , ⁸¹Ge , style="text-align:right" , 32 , style="text-align:right" , 49 , 80.92882(13) , 7.6(6) s , β⁻ , ⁸¹As , 9/2+# , , , - , rowspan=2 style="text-indent:1em" , ^81mGe , rowspan=2 colspan="3" style="text-indent:2em" , 679.13(4) keV , rowspan=2, 7.6(6) s , β⁻ (99%) , ⁸¹As , rowspan=2, (1/2+) , rowspan=2, , rowspan=2, , - , IT (1%) , ⁸¹Ge , - , ⁸²Ge , style="text-align:right" , 32 , style="text-align:right" , 50 , 81.92955(26) , 4.55(5) s , β⁻ , ⁸²As , 0+ , , , - , ⁸³Ge , style="text-align:right" , 32 , style="text-align:right" , 51 , 82.93462(21)# , 1.85(6) s , β⁻ , ⁸³As , (5/2+)# , , , - , rowspan=2, ⁸⁴Ge , rowspan=2 style="text-align:right" , 32 , rowspan=2 style="text-align:right" , 52 , rowspan=2, 83.93747(32)# , rowspan=2, 0.947(11) s , β⁻ (89.2%) , ⁸⁴As , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β⁻, n (10.8%) , ⁸³As , - , rowspan=2, ⁸⁵Ge , rowspan=2 style="text-align:right" , 32 , rowspan=2 style="text-align:right" , 53 , rowspan=2, 84.94303(43)# , rowspan=2, 535(47) ms , β⁻ (86%) , ⁸⁵As , rowspan=2, 5/2+# , rowspan=2, , rowspan=2, , - , β⁻, n (14%) , ⁸⁴As , - , rowspan=2, ⁸⁶Ge , rowspan=2 style="text-align:right" , 32 , rowspan=2 style="text-align:right" , 54 , rowspan=2, 85.94649(54)# , rowspan=2, >150 ns , β⁻, n , ⁸⁵As , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β⁻ , ⁸⁶As , - , ⁸⁷Ge , style="text-align:right" , 32 , style="text-align:right" , 55 , 86.95251(54)# , 0.14# s , , , 5/2+# , , , - , ⁸⁸Ge , style="text-align:right" , 32 , style="text-align:right" , 56 , 87.95691(75)# , >=300 ns , , , 0+ , , , - , ⁸⁹Ge , style="text-align:right" , 32 , style="text-align:right" , 57 , 88.96383(97)# , >150 ns , , , 3/2+# , , * Angular momentum or 3rd order sub particles are omitted as spin(2)=0,45,45.

References

* Isotope masses from: ** * Isotopic compositions and standard atomic masses from: ** ** * Half-life, spin, and isomer data selected from the following sources. ** ** ** {{Navbox element isotopes Germanium