Isotopes of ruthenium

Main isotopes of Chemistry:ruthenium (44Ru) | Iso­tope | Decay

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| abun­dance | half-life (t1/2) | mode | pro­duct
96Ru  | 5.54%  | stable
97Ru  | syn | 2.9 d | ε | 97Tc
γ | –
98Ru  | 1.87%  | stable
99Ru  | 12.76%  | stable
100Ru  | 12.60%  | stable
101Ru  | 17.06%  | stable
102Ru  | 31.55%  | stable
103Ru  | syn  | 39.26 d | β− | 103Rh
γ  | –
104Ru  | 18.62%  | stable
106Ru  | syn  | 373.59 d | β− | 106Rh
Standard atomic weight Ar, standard(Ru)|

* 101.07(2)[1]

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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 (RuO4), 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.[2][3][4] The two most important isotopes of ruthenium so released are those with the longest half-life: 103Ru 106Ru.[3]

Ruthenium-96

## Contents

* 1 List of isotopes
* 2 Alleged ruthenium-106 leak
* 3 Asteroid that ended the Cretaceous period
* 4 See also
* 5 References

## List of isotopes

Nuclide
[n 1] | Z | N | Isotopic mass (u)
[n 2][n 3] | Half-life
[n 4] | Decay
mode
[n 5] | Daughter
isotope
[n 6] | Spin and
parity
[n 7][n 4] | Physics:Natural abundance (mole fraction)

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Excitation energy[n 4] | Normal proportion  | Range of variation
85Ru  | 44  | 41  | 84.96712(54)#  | 2017 | 1# ms
[> 400 ns]  |  |  | 3/2−#  |  |
86Ru  | 44  | 42  | 85.95731(43)#  | 2017 | 50# ms
[> 400 ns]  |  |  | 0+  |  |
87Ru  | 44  | 43  | 86.95091(43)#  | 1995 | 50# ms
[> 1.5 μs]  |  |  | 1/2−#  |  |
88Ru  | 44  | 44  | 87.941760(20)[5] | 1994 | 1.5(3) s  | β+ (>96.4%)  | 88Tc  | 0+  |  |
β+, p (<3.6%)  | 87Mo
89Ru  | 44  | 45  | 88.937338(26)  | 1992 | 1.32(3) s  | β+ (96.7%)  | 89Tc  | (9/2+)  |  |
β+, p (3.1%)  | 88Mo
90Ru  | 44  | 46  | 89.9303444(40)  | 1991 | 11.7(9) s  | β+ | 90Tc  | 0+  |  |
91Ru  | 44  | 47  | 90.9267415(24)  | 1983 | 8.0(4) s  | β+ | 91Tc  | (9/2+)  |  |
91mRu  | 432(31) keV[6] | 1983 | 7.6(8) s  | β+ (>99.9%)  | 91Tc  | (1/2−)  |  |
β+, p (?%)  | 90Mo
92Ru  | 44  | 48  | 91.9202344(29)  | 1971 | 3.65(5) min  | β+ | 92Tc  | 0+  |  |
92mRu  | 2833.9(18) keV  | 1980 | 100(8) ns  | IT  | 92Ru  | (8+)  |  |
93Ru  | 44  | 49  | 92.9171044(22)  | 1972 | 59.7(6) s  | β+ | 93Tc  | (9/2)+  |  |
93m1Ru  | 734.40(10) keV  | 1976 | 10.8(3) s  | β+ (78.0%)  | 93Tc  | (1/2)−  |  |
IT (22.0%)  | 93Ru
β+, p (0.027%)  | 92Mo
93m2Ru  | 2082.5(9) keV  | 1983 | 2.30(7) μs  | IT  | 93Ru  | (21/2)+  |  |
94Ru  | 44  | 50  | 93.9113429(34)  | 1952 | 51.8(6) min  | β+ | 94Tc  | 0+  |  |
94mRu  | 2644.1(4) keV  | 1969 | 67.5(28) μs  | IT  | 94Ru  | 8+  |  |
95Ru  | 44  | 51  | 94.910404(10)  | 1948 | 1.607(4) h  | β+ | 95Tc  | 5/2+  |  |
96Ru  | 44  | 52  | 95.90758891(18)  | 1931 | Observationally Stable[n 8] | 0+  | 0.0554(14)  |
97Ru  | 44  | 53  | 96.9075458(30)  | 1946 | 2.8370(14) d  | β+ | 97Tc  | 5/2+  |  |
98Ru  | 44  | 54  | 97.9052867(69)  | 1944 | Stable | 0+  | 0.0187(3)  |
99Ru  | 44  | 55  | 98.90593028(37)  | 1931 | Stable | 5/2+  | 0.1276(14)  |
100Ru  | 44  | 56  | 99.90421046(37)  | 1931 | Stable | 0+  | 0.1260(7)  |
101Ru[n 9] | 44  | 57  | 100.90557309(44)  | 1931 | Stable | 5/2+  | 0.1706(2)  |
101mRu  | 527.56(10) keV  | 1964 | 17.5(4) μs  | IT  | 101Ru | 11/2−  |  |
102Ru[n 9] | 44  | 58  | 101.90434031(45)  | 1931 | Stable | 0+  | 0.3155(14)  |
103Ru[n 9] | 44  | 59  | 102.90631485(47)  | 1946 | 39.245(8) d  | β− | 103Rh | 3/2+  |  |
103mRu  | 238.2(7) keV  | 1964 | 1.69(7) ms  | IT  | 103Ru  | 11/2−  |  |
104Ru[n 9] | 44  | 60  | 103.9054253(27)  | 1931 | Observationally Stable[n 10] | 0+  | 0.1862(27)  |
105Ru[n 9] | 44  | 61  | 104.9077455(27)  | 1946 | 4.439(11) h  | β− | 105Rh  | 3/2+  |  |
105mRu  | 20.606(14) keV  | 1974 | 340(15) ns  | IT  | 105Ru  | 5/2+  |  |
106Ru[n 9] | 44  | 62  | 105.9073282(58)  | 1946 | 371.8(18) d  | β− | 106Rh  | 0+  |  |
107Ru  | 44  | 63  | 106.9099698(93)  | 1951 | 3.75(5) min  | β− | 107Rh  | (5/2)+  |  |
108Ru  | 44  | 64  | 107.9101858(93)  | 1955 | 4.55(5) min  | β− | 108Rh  | 0+  |  |
109Ru  | 44  | 65  | 108.9133237(96)  | 1967 | 34.4(2) s  | β− | 109Rh  | (5/2+)  |  |
109mRu  | 96.14(15) keV  | 1999 | 680(30) ns  | IT  | 109Ru  | (5/2−)  |  |
110Ru  | 44  | 66  | 109.9140385(96)  | 1970 | 12.04(17) s  | β− | 110Rh  | 0+  |  |
111Ru  | 44  | 67  | 110.917568(10)  | 1970 | 2.12(7) s  | β− | 111Rh  | 5/2+  |  |
112Ru  | 44  | 68  | 111.918807(10)  | 1970 | 1.75(7) s  | β− | 112Rh  | 0+  |  |
113Ru  | 44  | 69  | 112.922847(41)  | 1988 | 0.80(5) s  | β− | 113Rh  | (1/2+)  |  |
113mRu  | 131(33) keV  | 1998 | 510(30) ms  | β− (?%)  | 113Rh  | (7/2−)  |  |
IT (?%)  | 113Ru
114Ru  | 44  | 70  | 113.9246144(38)  | 1991 | 0.54(3) s  | β− | 114Rh  | 0+  |  |
β-, n?  | 113Rh
β-, 2n?  | 112Rh
115Ru  | 44  | 71  | 114.929033(27)  | 1992 | 318(19) ms  | β− | 115Rh  | (1/2+)  |  |
β-, n?  | 114Rh
115mRu  | 82(6) keV  | 2010 | 76(6) ms  | β− (?%)  | 115Rh  | (7/2−)  |  |
IT (?%)  | 115Ru
116Ru  | 44  | 72  | 115.9312192(40)  | 1994 | 204(6) ms  | β− | 116Rh  | 0+  |  |
β-, n?  | 115Rh
117Ru  | 44  | 73  | 116.93614(47)  | 1994 | 151(3) ms  | β− | 117Rh  | 3/2+#  |  |
β-, n?  | 116Rh
117mRu  | 185.0(4) keV  | 2012 | 2.49(6) μs  | IT  | 117Ru  | 7/2−#  |  |
118Ru  | 44  | 74  | 117.93881(22)#  | 1994 | 99(3) ms  | β− | 118Rh  | 0+  |  |
β-, n?  | 117Rh
119Ru  | 44  | 75  | 118.94409(32)#  | 1997 | 69.5(20) ms  | β− | 119Rh  | 3/2+#  |  |
β-, n?  | 118Rh
β-, 2n?  | 117Rh
119mRu  | 227.1(7) keV  | 2012 | 384(22) ns  | IT  | 119Ru  |  |  |
120Ru  | 44  | 76  | 119.94662(43)#  | 2010 | 45(2) ms  | β− | 120Rh  | 0+  |  |
121Ru  | 44  | 77  | 120.95210(43)#  | 2010 | 29(2) ms  | β− | 121Rh  | 3/2+#  |  |
122Ru  | 44  | 78  | 121.95515(54)#  | 2010 | 25(1) ms  | β− | 122Rh  | 0+  |  |
123Ru  | 44  | 79  | 122.96076(54)#  | 2010 | 19(2) ms  | β− | 123Rh  | 3/2+#  |  |
124Ru  | 44  | 80  | 123.96394(64)#  | 2010 | 15(3) ms  | β− | 124Rh  | 0+  |  |
125Ru  | 44  | 81  | 124.96954(32)#  | 2018 | 12# ms
[> 550 ns]  |  |  | 3/2+#  |  |

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. ↑ 4.0 4.1 4.2 # - 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

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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. ↑ 9.0 9.1 9.2 9.3 9.4 9.5 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.[7]

## 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.[8]

## See also

Daughter products other than ruthenium

* Isotopes of rhodium
* Isotopes of technetium
* Isotopes of molybdenum

## References

1. ↑ Meija, Juris; Coplen, Tyler B.; Berglund, Michael; Brand, Willi A.; De Bièvre, Paul; Gröning, Manfred; Holden, Norman E.; Irrgeher, Johanna et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry 88 (3): 265–91. doi:10.1515/pac-2015-0305.
2. ↑ Ronneau, C., Cara, J., & Rimski-Korsakov, A. (1995). Oxidation-enhanced emission of ruthenium from nuclear fuel. Journal of Environmental Radioactivity, 26(1), 63-70.
3. ↑ 3.0 3.1 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.
4. ↑ 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 . Nuclear Engineering and Design, 246, 157-162.
5. ↑ Kimura, S.; Wada, M.; Fu, C. Y.; Fukuda, N.; Hirayama, Y.; Hou, D. S.; Iimura, S.; Ishiyama, H. et al. (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. PMID 41138077.
6. ↑ Xing, Y. M.; Yuan, C. X.; Wang, M.; Zhang, Y. H.; Zhou, X. H.; Litvinov, Yu. A.; Blaum, K.; Xu, H. S. et al. (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.
7. ↑ [1] Detection of ruthenium 106 in France and in Europe, IRSN France (9 Nov 2017)
8. ↑ Dunham, Will (15 August 2024). "Asteroid that doomed the dinosaurs originated beyond Jupiter". https://www.theglobeandmail.com/world/article-asteroid-that-doomed-the-dinosaurs-originated-beyond-jupiter/. "ruthenium shows distinct isotopic compositions between inner and outer solar system materials"

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