Isotopes of ruthenium

Naturally occurring ruthenium (₄₄Ru) is composed of seven stable isotopes (of which two may in the future be found radioactive). Additionally, 27 radioactive isotopes have been discovered. Of these radioisotopes, the most stable are ¹⁰⁶Ru, with a half-life of 373.59 days; ¹⁰³Ru, with a half-life of 39.26 days and ⁹⁷Ru, with a half-life of 2.9 days.

Isotopes of ruthenium (₄₄Ru)

Main isotopes[1] Decay abun­dance half-life (t1/2) mode pro­duct 96Ru 5.54% stable 97Ru synth 2.9 d ε 97Tc γ – 98Ru 1.87% stable 99Ru 12.8% stable 100Ru 12.6% stable 101Ru 17.1% stable 102Ru 31.6% stable 103Ru synth 39.26 d β− 103Rh γ – 104Ru 18.6% stable 106Ru synth 373.59 d β− 106Rh
Standard atomic weight Ar°(Ru)
	101.07±0.02[2] 101.07±0.02 (abridged)[3]
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Twenty-four other radioisotopes have been characterized with atomic weights ranging from 86.95 u (⁸⁷Ru) to 119.95 u (¹²⁰Ru). Most of these have half-lives that are less than five minutes, except ⁹⁴Ru (half-life: 51.8 minutes), ⁹⁵Ru (half-life: 1.643 hours), and ¹⁰⁵Ru (half-life: 4.44 hours).

The primary decay mode before the most abundant isotope, ¹⁰²Ru, is electron capture and the primary mode after is beta emission. The primary decay product before ¹⁰²Ru is technetium and the primary product after is rhodium.

Because of the very high volatility of ruthenium tetroxide (RuO
₄) ruthenium radioactive isotopes with their relative short half-life are considered as the second most hazardous gaseous isotopes after iodine-131 in case of release by a nuclear accident.^[4][5][6] The two most important isotopes of ruthenium in case of nuclear accident are these with the longest half-life: ¹⁰³Ru (39.26 days) and ¹⁰⁶Ru (373.59 days).^[5]

List of isotopes

Nuclide [n 1]	Z	N	Isotopic mass (Da) [n 2][n 3]	Half-life [n 4]	Decay mode [n 5]	Daughter isotope [n 6]	Spin and parity [n 7][n 4]	Natural abundance (mole fraction)
	Excitation energy[n 4]							Normal proportion	Range of variation
87Ru	44	43	86.94918(64)#	50# ms [>1.5 μs]	β+	87Tc	1/2−#
88Ru	44	44	87.94026(43)#	1.3(3) s [1.2(+3−2) s]	β+	88Tc	0+
89Ru	44	45	88.93611(54)#	1.38(11) s	β+	89Tc	(7/2)(+#)
90Ru	44	46	89.92989(32)#	11.7(9) s	β+	90Tc	0+
91Ru	44	47	90.92629(63)#	7.9(4) s	β+	91Tc	(9/2+)
91mRu	80(300)# keV			7.6(8) s	β+ (>99.9%)	91Tc	(1/2−)
					IT (<.1%)	91Ru
					β+, p (<.1%)	90Mo
92Ru	44	48	91.92012(32)#	3.65(5) min	β+	92Tc	0+
93Ru	44	49	92.91705(9)	59.7(6) s	β+	93Tc	(9/2)+
93m1Ru	734.40(10) keV			10.8(3) s	β+ (78%)	93Tc	(1/2)−
					IT (22%)	93Ru
					β+, p (.027%)	92Mo
93m2Ru	2082.6(9) keV			2.20(17) μs			(21/2)+
94Ru	44	50	93.911360(14)	51.8(6) min	β+	94Tc	0+
94mRu	2644.55(25) keV			71(4) μs			(8+)
95Ru	44	51	94.910413(13)	1.643(14) h	β+	95Tc	5/2+
96Ru	44	52	95.907598(8)	Observationally Stable[n 8]			0+	0.0554(14)
97Ru	44	53	96.907555(9)	2.791(4) d	β+	97mTc	5/2+
98Ru	44	54	97.905287(7)	Stable			0+	0.0187(3)
99Ru	44	55	98.9059393(22)	Stable			5/2+	0.1276(14)
100Ru	44	56	99.9042195(22)	Stable			0+	0.1260(7)
101Ru[n 9]	44	57	100.9055821(22)	Stable			5/2+	0.1706(2)
101mRu	527.56(10) keV			17.5(4) μs			11/2−
102Ru[n 9]	44	58	101.9043493(22)	Stable			0+	0.3155(14)
103Ru[n 9]	44	59	102.9063238(22)	39.26(2) d	β−	103Rh	3/2+
103mRu	238.2(7) keV			1.69(7) ms	IT	103Ru	11/2−
104Ru[n 9]	44	60	103.905433(3)	Observationally Stable[n 10]			0+	0.1862(27)
105Ru[n 9]	44	61	104.907753(3)	4.44(2) h	β−	105Rh	3/2+
106Ru[n 9]	44	62	105.907329(8)	373.59(15) d	β−	106Rh	0+
107Ru	44	63	106.90991(13)	3.75(5) min	β−	107Rh	(5/2)+
108Ru	44	64	107.91017(12)	4.55(5) min	β−	108Rh	0+
109Ru	44	65	108.91320(7)	34.5(10) s	β−	109Rh	(5/2+)#
110Ru	44	66	109.91414(6)	11.6(6) s	β−	110Rh	0+
111Ru	44	67	110.91770(8)	2.12(7) s	β−	111Rh	(5/2+)
112Ru	44	68	111.91897(8)	1.75(7) s	β−	112Rh	0+
113Ru	44	69	112.92249(8)	0.80(5) s	β−	113Rh	(5/2+)
113mRu	130(18) keV			510(30) ms			(11/2−)
114Ru	44	70	113.92428(25)#	0.53(6) s	β− (>99.9%)	114Rh	0+
					β−, n (<.1%)	113Rh
115Ru	44	71	114.92869(14)	740(80) ms	β− (>99.9%)	115Rh
					β−, n (<.1%)	114Rh
116Ru	44	72	115.93081(75)#	400# ms [>300 ns]	β−	116Rh	0+
117Ru	44	73	116.93558(75)#	300# ms [>300 ns]	β−	117Rh
118Ru	44	74	117.93782(86)#	200# ms [>300 ns]	β−	118Rh	0+
119Ru	44	75	118.94284(75)#	170# ms [>300 ns]
120Ru	44	76	119.94531(86)#	80# ms [>300 ns]			0+
This table header & footer: view

1. ^mRu – 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. # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
5. Modes of decay:

   IT:	Isomeric transition
   n:	Neutron emission
   p:	Proton emission

6. Bold symbol as daughter – Daughter product is stable.
7. ( ) spin value – Indicates spin with weak assignment arguments.
8. Believed to undergo β⁺β⁺ decay to ⁹⁶Mo with a half-life over 6.7×10¹⁶ years
9. Fission product
10. Believed to undergo β⁻β⁻ decay to ¹⁰⁴Pd

• Geologically exceptional samples are known in which the isotopic composition lies outside the reported range. The uncertainty in the atomic mass may exceed the stated value for such specimens.^{[citation needed]}
• In September 2017 an estimated amount of 100 to 300 TBq (0.3 to 1 g) of ¹⁰⁶Ru was released in Russia, probably in the Ural region. It was, after ruling out release from a reentering satellite, concluded that the source is to be found either in nuclear fuel cycle facilities or radioactive source production. In France levels up to 0.036mBq/m³ of air were measured. It is estimated that over distances of the order of a few tens of kilometres around the location of the release levels may exceed the limits for non-dairy foodstuffs.^[7]

Ruthenium-96

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: Ruthenium". CIAAW. 1983.
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. Ronneau, C., Cara, J., & Rimski-Korsakov, A. (1995). Oxidation-enhanced emission of ruthenium from nuclear fuel. Journal of Environmental Radioactivity, 26(1), 63-70.
5. Backman, U., Lipponen, M., Auvinen, A., Jokiniemi, J., & Zilliacus, R. (2004). Ruthenium behaviour in severe nuclear accident conditions. Final report (No. NKS–100). Nordisk Kernesikkerhedsforskning.
6. Beuzet, E., Lamy, J. S., Perron, H., Simoni, E., & Ducros, G. (2012). Ruthenium release modelling in air and steam atmospheres under severe accident conditions using the MAAP4 code^{[dead link]}. Nuclear Engineering and Design, 246, 157-162.
7. Detection of ruthenium 106 in France and in Europe, IRSN France (9 Nov 2017)

• 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:
  • de Laeter, John Robert; Böhlke, John Karl; De Bièvre, Paul; Hidaka, Hiroshi; Peiser, H. Steffen; Rosman, Kevin J. R.; Taylor, Philip D. P. (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
  • Wieser, Michael E. (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051.
• "News & Notices: Standard Atomic Weights Revised". International Union of Pure and Applied Chemistry. 19 October 2005.
• Half-life, spin, and isomer data selected from the following sources.
  • 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
  • National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
  • Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.