Isotopes of germanium

Germanium (Ge) 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^[1] (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%.^[2] When bombarded with alpha particles, the isotopes ⁷²Ge and ⁷⁶Ge will generate stable ⁷⁵As and ⁷⁷Se, releasing high energy electrons in the process.^[3]

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.^{[2] 84}Ge through ⁸⁷Ge also have minor β⁻ delayed neutron emission decay paths.^[2]

Relative atomic mass: 72.630(8)

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life[n 1]	decay mode(s)[4][n 2]	daughter isotope(s)[n 3]	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
	excitation energy
^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 4]	32	36	67.928094(7)	270.95(16) d	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 5]	32	44	75.9214026(18)	1.78(8)×10^21 y	β^−β^−	^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. 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
4. Used to generate ⁶⁸Ga
5. Primordial radionuclide

Notes

• 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.
• Angular momentum or 3rd order sub particles are omitted as spin(2)=0,45,45.
• 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.
• Nuclide masses are given by IUPAP Commission on Symbols, Units, Nomenclature, Atomic Masses and Fundamental Constants (SUNAMCO).
• Isotope abundances are given by IUPAC Commission on Isotopic Abundances and Atomic Weights.

References

• Isotope masses from:
  • G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). 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:
  • J. R. de Laeter; J. K. Böhlke; P. De Bièvre; H. Hidaka; H. S. Peiser; K. J. R. Rosman; P. D. P. Taylor (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry 75 (6): 683–800. doi:10.1351/pac200375060683.
  • M. E. Wieser (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry 78 (11): 2051–2066. doi:10.1351/pac200678112051. Lay summary.
• Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
  • G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001.
  • National Nuclear Data Center. "NuDat 2.3 database". Brookhaven National Laboratory. Retrieved August 2007.
  • N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide. CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0-8493-0485-9.

1. 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.
2. G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001.
3. 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
4. "Universal Nuclide Chart". nucleonica. (registration required (help)).