Isotopes of ruthenium

Isotopes of ruthenium  (₄₄Ru)

Main isotopes [1] Decay Isotope abun­dance half-life (t1/2) mode pro­duct 96Ru 5.54% stable 97Ru synth 2.837 d ε 97Tc 98Ru 1.87% stable 99Ru 12.8% stable 100Ru 12.6% stable 101Ru 17.1% stable 102Ru 31.6% stable 103Ru synth 39.245 d β− 103Rh 104Ru 18.6% stable 106Ru synth 371.8 d β− 106Rh
Standard atomic weight Ar°(Ru)
	101.07±0.02 [2] 101.07±0.02 (abridged) [3]
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Naturally occurring ruthenium (₄₄Ru) is composed of seven stable isotopes: 96, 98-102, 104 (of which the first and last may in the future be found radioactive). Additionally, 27 synthetic radioactive isotopes have been discovered. Of these radioisotopes, the most stable are ¹⁰⁶Ru with a half-life of 371.8 days or 1.018 years, ¹⁰³Ru, with a half-life of 39.245 days, and ⁹⁷Ru with a half-life of 2.837 days.

The other known isotopes run from ⁸⁷Ru to ¹²⁰Ru, and most of these have half-lives that are less than five minutes, except ⁹⁴Ru (51.8 minutes), ⁹⁵Ru (1.607 hours), and ¹⁰⁵Ru (4.44 hours).

The primary decay mode before the most abundant isotope, ¹⁰²Ru, is electron capture to isotopes of technetium, and after beta emission to isotopes of rhodium. Double beta decay is the allowed mode for the two observationally stable isotopes: ⁹⁶Ru and ¹⁰⁴Ru.

Because of the volatility of ruthenium tetroxide (RuO
_⁴), ruthenium isotopes with relatively short half-life are considered the next most hazardous airborne isotopes, after iodine-131, in case of release by a nuclear accident. ^{[4] [5] [6]} The two most important isotopes of ruthenium so released are those with the longest half-life: ¹⁰³Ru ¹⁰⁶Ru. ^[5]

Ruthenium-96

List of isotopes

Nuclide [n 1]	Z	N	Isotopic mass (Da) [7] [n 2] [n 3]	Half-life [1] [n 4]	Decay mode [1] [n 5]	Daughter isotope [n 6]	Spin and parity [1] [n 7] [n 4]	Natural abundance (mole fraction)
	Excitation energy [n 4]							Normal proportion [1]	Range of variation
85Ru	44	41	84.96712(54)#	1# ms [> 400 ns]			3/2−#
86Ru	44	42	85.95731(43)#	50# ms [> 400 ns]			0+
87Ru	44	43	86.95091(43)#	50# ms [> 1.5 μs]			1/2−#
88Ru	44	44	87.941760(20) [8]	1.5(3) s	β+ (>96.4%)	88Tc	0+
					β+, p (<3.6%)	87Mo
89Ru	44	45	88.937338(26)	1.32(3) s	β+ (96.7%)	89Tc	(9/2+)
					β+, p (3.1%)	88Mo
90Ru	44	46	89.9303444(40)	11.7(9) s	β+	90Tc	0+
91Ru	44	47	90.9267415(24)	8.0(4) s	β+	91Tc	(9/2+)
91mRu	432(31) keV [9]			7.6(8) s	β+ (>99.9%)	91Tc	(1/2−)
					β+, p (?%)	90Mo
92Ru	44	48	91.9202344(29)	3.65(5) min	β+	92Tc	0+
92mRu	2833.9(18) keV			100(8) ns	IT	92Ru	(8+)
93Ru	44	49	92.9171044(22)	59.7(6) s	β+	93Tc	(9/2)+
93m1Ru	734.40(10) keV			10.8(3) s	β+ (78.0%)	93Tc	(1/2)−
					IT (22.0%)	93Ru
					β+, p (0.027%)	92Mo
93m2Ru	2082.5(9) keV			2.30(7) μs	IT	93Ru	(21/2)+
94Ru	44	50	93.9113429(34)	51.8(6) min	β+	94Tc	0+
94mRu	2644.1(4) keV			67.5(28) μs	IT	94Ru	8+
95Ru	44	51	94.910404(10)	1.607(4) h	β+	95Tc	5/2+
96Ru	44	52	95.90758891(18)	Observationally Stable [n 8]			0+	0.0554(14)
97Ru	44	53	96.9075458(30)	2.8370(14) d	β+	97Tc	5/2+
98Ru	44	54	97.9052867(69)	Stable			0+	0.0187(3)
99Ru	44	55	98.90593028(37)	Stable			5/2+	0.1276(14)
100Ru	44	56	99.90421046(37)	Stable			0+	0.1260(7)
101Ru [n 9]	44	57	100.90557309(44)	Stable			5/2+	0.1706(2)
101mRu	527.56(10) keV			17.5(4) μs	IT	101Ru	11/2−
102Ru [n 9]	44	58	101.90434031(45)	Stable			0+	0.3155(14)
103Ru [n 9]	44	59	102.90631485(47)	39.245(8) d	β−	103Rh	3/2+
103mRu	238.2(7) keV			1.69(7) ms	IT	103Ru	11/2−
104Ru [n 9]	44	60	103.9054253(27)	Observationally Stable [n 10]			0+	0.1862(27)
105Ru [n 9]	44	61	104.9077455(27)	4.439(11) h	β−	105Rh	3/2+
105mRu	20.606(14) keV			340(15) ns	IT	105Ru	5/2+
106Ru [n 9]	44	62	105.9073282(58)	371.8(18) d	β−	106Rh	0+
107Ru	44	63	106.9099698(93)	3.75(5) min	β−	107Rh	(5/2)+
108Ru	44	64	107.9101858(93)	4.55(5) min	β−	108Rh	0+
109Ru	44	65	108.9133237(96)	34.4(2) s	β−	109Rh	(5/2+)
109mRu	96.14(15) keV			680(30) ns	IT	109Ru	(5/2−)
110Ru	44	66	109.9140385(96)	12.04(17) s	β−	110Rh	0+
111Ru	44	67	110.917568(10)	2.12(7) s	β−	111Rh	5/2+
112Ru	44	68	111.918807(10)	1.75(7) s	β−	112Rh	0+
113Ru	44	69	112.922847(41)	0.80(5) s	β−	113Rh	(1/2+)
113mRu	131(33) keV			510(30) ms	β− (?%)	113Rh	(7/2−)
					IT (?%)	113Ru
114Ru	44	70	113.9246144(38)	0.54(3) s	β−	114Rh	0+
					β-, n?	113Rh
					β-, 2n?	112Rh
115Ru	44	71	114.929033(27)	318(19) ms	β−	115Rh	(1/2+)
					β-, n?	114Rh
115mRu	82(6) keV			76(6) ms	β− (?%)	115Rh	(7/2−)
					IT (?%)	115Ru
116Ru	44	72	115.9312192(40)	204(6) ms	β−	116Rh	0+
					β-, n?	115Rh
117Ru	44	73	116.93614(47)	151(3) ms	β−	117Rh	3/2+#
					β-, n?	116Rh
117mRu	185.0(4) keV			2.49(6) μs	IT	117Ru	7/2−#
118Ru	44	74	117.93881(22)#	99(3) ms	β−	118Rh	0+
					β-, n?	117Rh
119Ru	44	75	118.94409(32)#	69.5(20) ms	β−	119Rh	3/2+#
					β-, n?	118Rh
					β-, 2n?	117Rh
119mRu	227.1(7) keV			384(22) ns	IT	119Ru
120Ru	44	76	119.94662(43)#	45(2) ms	β−	120Rh	0+
121Ru	44	77	120.95210(43)#	29(2) ms	β−	121Rh	3/2+#
122Ru	44	78	121.95515(54)#	25(1) ms	β−	122Rh	0+
123Ru	44	79	122.96076(54)#	19(2) ms	β−	123Rh	3/2+#
124Ru	44	80	123.96394(64)#	15(3) ms	β−	124Rh	0+
125Ru	44	81	124.96954(32)#	12# ms [> 550 ns]			3/2+#
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 8×10¹⁹ years
9. Fission product
10. Believed to undergo β⁻β⁻ decay to ¹⁰⁴Pd

Alleged ruthenium-106 leak

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 was either in nuclear fuel cycle facilities or radioactive source production. In France levels up to 0.036mBq/m³ of air were measured. It was estimated that for distances of the order of a few tens of kilometres, contamination levels may have exceeded the limits for non-dairy foodstuffs. ^[10]

Asteroid that ended the Cretaceous period

The ratios of the amounts of ruthenium isotopes were used to determine the age of the asteroid which exterminated the dinosaurs at the end of the Cretaceous period, and to show that it originated beyond Jupiter in the outer solar system. ^[11]

See also

Daughter products other than ruthenium

• Isotopes of rhodium
• Isotopes of technetium
• Isotopes of molybdenum

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. 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.
8. Kimura, S.; Wada, M.; Fu, C. Y.; Fukuda, N.; Hirayama, Y.; Hou, D. S.; Iimura, S.; Ishiyama, H.; Ito, Y.; Kubono, S.; Kusaka, K.; Michimasa, S.; Miyatake, H.; Nishimura, S.; Niwase, T.; Phong, V.; Rosenbusch, M.; Schatz, H.; Schury, P.; Shimizu, Y.; Suzuki, H.; Takamine, A.; Takeda, H.; Togano, Y.; Watanabe, Y. X.; Xian, W. D.; Yanagisawa, Y.; Yeung, T. T.; Yoshimoto, M.; Zha, S. (8 October 2025). "Precision Mass Measurements around Mo 84 Rule Out ZrNb Cycle Formation in the Rapid Proton-Capture Process at Type I X-Ray Bursts". Physical Review Letters. 135 (15). doi:10.1103/2dyn-q7wp.
9. Xing, Y. M.; Yuan, C. X.; Wang, M.; Zhang, Y. H.; Zhou, X. H.; Litvinov, Yu. A.; Blaum, K.; Xu, H. S.; Bao, T.; Chen, R. J.; Fu, C. Y.; Gao, B. S.; Ge, W. W.; He, J. J.; Huang, W. J.; Liao, T.; Li, J. G.; Li, H. F.; Litvinov, S.; Naimi, S.; Shuai, P.; Sun, M. Z.; Wang, Q.; Xu, X.; Xu, F. R.; Yamaguchi, T.; Yan, X. L.; Yang, J. C.; Yuan, Y. J.; Zeng, Q.; Zhang, M.; Zhou, X. (11 January 2023). "Isochronous mass measurements of neutron-deficient nuclei from Sn 112 projectile fragmentation". Physical Review C. 107 (1). doi:10.1103/PhysRevC.107.014304.
10. Detection of ruthenium 106 in France and in Europe, IRSN France (9 Nov 2017)
11. Dunham, Will (15 August 2024). "Asteroid that doomed the dinosaurs originated beyond Jupiter". The Globe and Mail. Retrieved 8 July 2025. ruthenium shows distinct isotopic compositions between inner and outer solar system materials