Isotopes of germanium

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^[4] (130 billion times the age of the universe).

Isotopes of germanium (₃₂Ge)

Main isotopes^[1] Decay abun­dance half-life (t1/2) mode pro­duct ^68Ge synth 270.8 d ε ^68Ga ^70Ge 20.5% stable ^71Ge synth 11.3 d ε ^71Ga ^72Ge 27.4% stable ^73Ge 7.76% stable ^74Ge 36.5% stable ^76Ge 7.75% 1.78×10^21 y β^−β^− ^76Se
Standard atomic weight Ar°(Ge)
	72.630±0.008^[2] 72.630±0.008 (abridged)^[3]
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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%.^[5]

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 ⁵⁹Ge with a half-life of 13.3 ms.

While most of germanium's radioisotopes decay by beta decay, ⁶¹Ge and ⁶⁵Ge can also decay by β⁺-delayed proton emission.^{[5] 84}Ge through ⁸⁷Ge also have minor β⁻-delayed neutron emission decay paths.^[5]

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

List of isotopes

Nuclide ^[n 1]	Z	N	Isotopic mass (Da)^[6] ^[n 2]^[n 3]	Half-life^[1] ^[n 4]^[n 5]	Decay mode^[1] ^[n 6]	Daughter isotope ^[n 7]	Spin and parity^[1] ^[n 8]^[n 5]	Natural abundance (mole fraction)
	Excitation energy							Normal proportion^[1]	Range of variation
^59Ge	32	27	58.98243(43)#	13.3(17) ms	β^+, p (93%)	^58Zn	7/2−#
					β^+ (7%)	^59Ga
					2p?	^57Zn
^60Ge	32	28	59.97045(32)#	21(6) ms	β^+, p	^59Zn	0+
					β^+, 2p? (<14%)	^58Cu
^61Ge	32	29	60.96373(32)#	40.7(4) ms	β^+, p (87%)	^60Zn	3/2−#
					β^+ (18%)	^61Ga
^62Ge	32	30	61.95476(15)#	82.5(14) ms	β^+	^62Ga	0+
					β^+, p?	^61Zn
^63Ge	32	31	62.949628(40)	153.6(11) ms	β^+	^63Ga	3/2−#
					β^+, p?	^62Zn
^64Ge	32	32	63.9416899(40)	63.7(25) s	β^+	^64Ga	0+
^65Ge	32	33	64.9393681(23)	30.9(5) s	β^+ (99.99%)	^65Ga	3/2−
					β^+, p (0.011%)	^64Zn
^66Ge	32	34	65.9338621(26)	2.26(5) h	β^+	^66Ga	0+
^67Ge	32	35	66.9327170(46)	18.9(3) min	β^+	^67Ga	1/2−
^67m1Ge	18.20(5) keV			13.7(9) μs	IT	^67Ge	5/2−
^67m2Ge	751.70(6) keV			109.1(38) ns	IT	^67Ge	9/2+
^68Ge^[n 9]	32	36	67.9280953(20)	271.05(8) d	EC	^68Ga	0+
^69Ge	32	37	68.9279645(14)	39.05(10) h	β^+	^69Ga	5/2−
^69m1Ge	86.76(2) keV			5.1(2) μs	IT	^69Ge	1/2−
^69m2Ge	397.94(2) keV			2.81(5) μs	IT	^69Ge	9/2+
^70Ge	32	38	69.92424854(88)	Stable			0+	0.2052(19)
^71Ge	32	39	70.92495212(87)	11.43(3) d	EC	^71Ga	1/2−
^71mGe	198.354(14) keV			20.41(18) ms	IT	^71Ge	9/2+
^72Ge	32	40	71.922075824(81)	Stable			0+	0.2745(15)
^72mGe	691.43(4) keV			444.2(8) ns	IT	^72Ge	0+
^73Ge	32	41	72.923458954(61)	Stable			9/2+	0.0776(8)
^73m1Ge	13.2845(15) keV			2.91(3) μs	IT	^73Ge	5/2+
^73m2Ge	66.725(9) keV			499(11) ms	IT	^73Ge	1/2−
^74Ge	32	42	73.921177760(13)	Stable			0+	0.3652(12)
^75Ge	32	43	74.922858370(55)	82.78(4) min	β^−	^75As	1/2−
^75m1Ge	139.69(3) keV			47.7(5) s	IT (99.97%)	^75Ge	7/2+
					β^− (0.030%)	^75As
^75m2Ge	192.19(6) keV			216(5) ns	IT	^75Ge	5/2+
^76Ge^[n 10]	32	44	75 921402.725(19)	(2.022±0.018±0.038)×10^21 y^[7]	β^−β^−	^76Se	0+	0.0775(12)
^77Ge	32	45	76 923549.843(56)	11.211(3) h	β^−	^77As	7/2+
^77mGe	159.71(6) keV			53.7(6) s	β^− (81%)	^77As	1/2−
					IT (19%)	^77Ge
^78Ge	32	46	77.9228529(38)	88.0(10) min	β^−	^78As	0+
^79Ge	32	47	78.925360(40)	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	79.9253508(22)	29.5(4) s	β^−	^80As	0+
^81Ge	32	49	80.9288329(22)	9(2) s	β^−	^81As	9/2+#
^81mGe	679.14(4) keV			6(2) s	β^−	^81As	(1/2+)
					IT? (<1%)	^81Ge
^82Ge	32	50	81.9297740(24)	4.31(19) s	β^−	^82As	0+
^83Ge	32	51	82.9345391(26)	1.85(6) s	β^−	^83As	(5/2+)
					β^−, n?	^82As
^84Ge	32	52	83.9375751(34)	951(9) ms	β^− (89.4%)	^84As	0+
					β^−, n (10.6%)	^83As
^85Ge	32	53	84.9429697(40)	495(5) ms	β^− (82.8%)	^85As	(3/2+,5/2+)#
					β^−, n (17.2%)	^84As
					β^−, 2n?	^83As
^86Ge	32	54	85.94697(47)	221.6(11) ms	β^− (55%)	^86As	0+
					β^−, n (45%)	^85As
^87Ge	32	55	86.95320(32)#	103(4) ms	β^−	^87As	5/2+#
					β^−, n?	^86As
					β^−, 2n?	^85As
^88Ge	32	56	87.95757(43)#	61(6) ms	β^−	^88As	0+
					β^−, n?	^87As
					β^−, 2n?	^86As
^89Ge	32	57	88.96453(43)#	60# ms [>300 ns]	β^−?	^89As	3/2+#
					β^−, n?	^88As
					β^−, 2n?	^87As
^90Ge	32	57	89.96944(54)#	30# ms [>400 ns]	β^−?	^90As	0+
					β^−, n?	^89As
					β^−, 2n?	^88As
^91Ge^[8]	32	59
^92Ge^[8]	32	60
This table header & footer: view

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. # – 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

References

1. Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
2. "Standard Atomic Weights: Germanium". CIAAW. 2009.
3. Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
4. 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.
5. 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
6. Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.
7. M. Agostini; et al. (2023-10-03). "Final Results of GERDA on the Two-Neutrino Double-β Decay Half-Life of ⁷⁶Ge". Physical Review Letters. 131 (14). American Physical Society (APS): 142501. arXiv:2308.09795. Bibcode:2023PhRvL.131n2501A. doi:10.1103/physrevlett.131.142501. ISSN 0031-9007. PMID 37862664. S2CID 261049638.
8. Shimizu, Y.; Kubo, T.; Sumikama, T.; Fukuda, N.; Takeda, H.; Suzuki, H.; Ahn, D. S.; Inabe, N.; Kusaka, K.; Ohtake, M.; Yanagisawa, Y.; Yoshida, K.; Ichikawa, Y.; Isobe, T.; Otsu, H.; Sato, H.; Sonoda, T.; Murai, D.; Iwasa, N.; Imai, N.; Hirayama, Y.; Jeong, S. C.; Kimura, S.; Miyatake, H.; Mukai, M.; Kim, D. G.; Kim, E.; Yagi, A. (8 April 2024). "Production of new neutron-rich isotopes near the N = 60 isotones Ge 92 and As 93 by in-flight fission of a 345 MeV/nucleon U 238 beam". Physical Review C. 109 (4). doi:10.1103/PhysRevC.109.044313.