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)[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	87.94166(32)#	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[n 8]	−340(500) keV			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 9]			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 10]	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 10]	44	58	101.90434031(45)	Stable			0+	0.3155(14)
103Ru[n 10]	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 10]	44	60	103.9054253(27)	Observationally Stable[n 11]			0+	0.1862(27)
105Ru[n 10]	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 10]	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+
115Ru	44	71	114.929033(27)	318(19) ms	β−	115Rh	(1/2+)
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+
117Ru	44	73	116.93614(47)	151(3) ms	β−	117Rh	3/2+#
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+
119Ru	44	75	118.94409(32)#	69.5(20) ms	β−	119Rh	3/2+#
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. Order of ground state and isomer is uncertain.
9. Believed to undergo β⁺β⁺ decay to ⁹⁶Mo with a half-life over 8×10¹⁹ years
10. Fission product
11. Believed to undergo β⁻β⁻ decay to ¹⁰⁴Pd

• 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.^[8]

Ruthenium-96