Isotopes of ruthenium

Naturally occurring ruthenium (Ru) is composed of seven stable isotopes. 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.

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, excepting 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.

Relative atomic mass: 101.07(2).

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)	daughter isotope(s)	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
	excitation energy
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			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	44	57	100.9055821(22)	Stable			5/2+	0.1706(2)
101mRu	527.56(10) keV			17.5(4) µs			11/2−
102Ru	44	58	101.9043493(22)	Stable			0+	0.3155(14)
103Ru	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	44	60	103.905433(3)	Observationally Stable			0+	0.1862(27)
105Ru	44	61	104.907753(3)	4.44(2) h	β−	105Rh	3/2+
106Ru	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+

Notes

• 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.
• 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.
• 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.

References

• Isotope masses from:
• Isotopic compositions and standard atomic masses from:
• Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.

Isotopes of technetium	Isotopes of ruthenium	Isotopes of rhodium
Table of nuclides