Isotopes of cadmium

Naturally occurring cadmium (₄₈Cd) is composed of 8 isotopes. For two of them, natural radioactivity has been observed, and three others are predicted to possibly decay though this has not been observed; it may be presumed the half-lives are extremely long. The two natural radioactive isotopes are ¹¹³Cd (beta decay, half-life 8.04×10¹⁵ years) and ¹¹⁶Cd (double beta decay, half-life 2.69×10¹⁹ years). The other three are ¹⁰⁶Cd, ¹⁰⁸Cd (double electron capture), and ¹¹⁴Cd (double beta decay); only lower limits on their decays have been set. Only three isotopes—^110-112Cd—are theoretically stable. Among the isotopes absent in natural cadmium, the most long-lived are ¹⁰⁹Cd with a half-life of 461.3 days, and ¹¹⁵Cd with a half-life of 53.46 hours. All of the remaining radioactive isotopes have half-lives that are less than 2.5 hours and the majority of these are less than 5 minutes. This element also has 12 known meta states, with the most stable being ^113mCd (t_1/2 13.9 years), ^115mCd (t_1/2 44.6 days) and ^117mCd (t_1/2 3.44 hours).

Isotopes of cadmium (₄₈Cd)

Main isotopes[1] Decay abun­dance half-life (t1/2) mode pro­duct 106Cd 1.25% stable 107Cd synth 6.50 h ε 107Ag 108Cd 0.89% stable 109Cd synth 461.3 d ε 109Ag 110Cd 12.5% stable 111Cd 12.8% stable 112Cd 24.1% stable 113Cd 12.2% 8.04×1015 y β− 113In 113mCd synth 13.9 y β− 113In IT 113Cd 114Cd 28.8% stable 115Cd synth 53.46 h β− 115In 116Cd 7.51% 2.69×1019 y β−β− 116Sn
Standard atomic weight Ar°(Cd)
	112.414±0.004[2] 112.41±0.01 (abridged)[3]
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The known isotopes of cadmium range from ⁹⁵Cd to ¹³²Cd. The primary decay mode before the stable isotope ¹¹²Cd is electron capture to isotopes of silver, and after, beta emission to isotopes of indium.

A 2021 study has shown at high ionic strengths, Cd isotope fractionation mainly depends on its complexation with carboxylic sites. At low ionic strengths, nonspecific Cd binding induced by electrostatic attractions plays a dominant role and promotes Cd isotope fractionation during complexation.[4]

List of isotopes

Nuclide [n 1]	Z	N	Isotopic mass (Da)[5] [n 2][n 3]	Half-life[1] [n 4]	Decay mode[1] [n 5]	Daughter isotope [n 6][n 7]	Spin and parity[1] [n 8][n 9]	Natural abundance (mole fraction)
	Excitation energy[n 9]							Normal proportion[1]	Range of variation
94Cd	48	46	93.95659(54)#	80# ms [> 760 ns]			0+
95Cd	48	47	94.94948(61)#	32(3) ms	β+ (95.4%)	95Ag	9/2+#
					β+, p (4.6%)	94Pd
96Cd	48	48	95.94034(44)#	1.003(47) s	β+ (98.4%)	96Ag	0+
					β+, p (1.6%)	95Pd
96m1Cd	6000(1400) keV			511(26) ms	β+ (84.6%)	96Ag	16+
					β+, p (15.4%)	95Pd
96m2Cd	5605(5) keV			198(18) ns	IT	96Cd	(12−,13−)
97Cd	48	49	96.93480(45)	1.16(5) s	β+ (92.6%)	97Ag	(9/2+)
					β+, p (7.4%)	96Pd
97m1Cd	1245.1(2) keV			730(70) μs	IT	97Cd	(1/2−)
97m2Cd	2620(580) keV			3.86(6) s	β+ (74.9%)	97Ag	(25/2+)
					β+, p (25.1%)	96Pd
98Cd	48	50	97.927389(56)	9.29(10) s	β+ (>99.97%)	98Ag	0+
					β+, p (<0.029%)	97Pd
98m1Cd	2428.3(4) keV			154(16) ns	IT	98Cd	(8+)
98m2Cd	6635(2) keV			224(5) ns	IT	98Cd	(12+)
99Cd	48	51	98.9249258(17)	17(1) s	β+ (99.79%)	99Ag	5/2+#
					β+, p (0.21%)	98Pd
					β+, α (<10−4%)	95Rh
100Cd	48	52	99.9203488(18)	49.1(5) s	β+	100Ag	0+
101Cd	48	53	100.9185862(16)	1.36(5) min	β+	101Ag	5/2+
102Cd	48	54	101.9144818(18)	5.5(5) min	β+	102Ag	0+
103Cd	48	55	102.9134169(19)	7.3(1) min	β+	103Ag	5/2+
104Cd	48	56	103.9098562(18)	57.7(10) min	β+	104Ag	0+
105Cd	48	57	104.9094639(15)	55.5(4) min	β+	105Ag	5/2+
105mCd	2517.6(5) keV			4.5(5) μs	IT	105Cd	(21/2+)
106Cd	48	58	105.9064598(12)	Observationally stable[n 10]			0+	0.01245(22)
107Cd	48	59	106.9066120(18)	6.50(2) h	β+	107Ag	5/2+
108Cd	48	60	107.9041836(12)	Observationally stable[n 11]			0+	0.00888(11)
109Cd	48	61	108.9049867(16)	461.3(5) d	EC	109Ag	5/2+
109m1Cd	59.60(7) keV			11.8(16) μs	IT	109Cd	1/2+
109m2Cd	463.10(11) keV			10.6(4) μs	IT	109Cd	11/2−
110Cd	48	62	109.90300747(41)	Stable			0+	0.12470(61)
111Cd[n 12]	48	63	110.90418378(38)	Stable			1/2+	0.12795(12)
111mCd	396.214(21) keV			48.50(9) min	IT	111Cd	11/2−
112Cd[n 12]	48	64	111.90276390(27)	Stable			0+	0.24109(7)
113Cd[n 12][n 13]	48	65	112.90440811(26)	8.04(5)×1015 y	β−	113In	1/2+	0.12227(7)
113mCd[n 12]	263.54(3) keV			13.89(11) y	β− (99.90%)	113In	11/2−
					IT (0.0964%)	113Cd
114Cd[n 12]	48	66	113.90336500(30)	Observationally stable[n 14]			0+	0.28754(81)
115Cd[n 12]	48	67	114.90543743(70)	53.46(5) h	β−	115mIn	1/2+
115mCd[n 12]	181.0(5) keV			44.56(24) d	β−	115In	11/2−
116Cd[n 12][n 13]	48	68	115.90476323(17)	2.69(9)×1019 y	β−β−	116Sn	0+	0.07512(54)
117Cd	48	69	116.9072260(11)	2.503(5) h	β−	117In	1/2+
117mCd	136.4(2) keV			3.441(9) h	β−	117In	11/2−
118Cd	48	70	117.906922(21)	50.3(2) min	β−	118In	0+
119Cd	48	71	118.909847(40)	2.69(2) min	β−	119In	1/2+
119mCd	146.54(11) keV			2.20(2) min	β−	119In	11/2−
120Cd	48	72	119.9098681(40)	50.80(21) s	β−	120In	0+
121Cd	48	73	120.9129637(21)	13.5(3) s	β−	121In	3/2+
121mCd	214.86(15) keV			8.3(8) s	β−	121In	11/2−
122Cd	48	74	121.9134591(25)	5.98(10) s[6]	β−	122In	0+
123Cd	48	75	122.9168925(29)	2.10(2) s	β−	123In	3/2+
123mCd	143(4) keV			1.82(3) s	β− (?%)	123In	11/2−
					IT (?%)	123Cd
124Cd	48	76	123.9176598(28)	1.25(2) s	β−	124In	0+
125Cd	48	77	124.9212576(31)	680(40) ms	β−	125In	3/2+
125m1Cd	186(4) keV			480(30) ms	β−	125In	11/2−
125m2Cd	1648(4) keV			19(3) μs	IT	125Cd	(19/2+)
126Cd	48	78	125.9224303(25)	512(5) ms	β−	126In	0+
127Cd	48	79	126.9262033(67)	480(100) ms	β−	127In	3/2+
127m1Cd	285(8) keV			360(40) ms	β−	127In	11/2−
127m2Cd	1845(8) keV			17.5(3) μs	IT	127Cd	(19/2+)
128Cd	48	80	127.9278168(69)	246(2) ms	β−	128In	0+
128m1Cd	1870.5(3) keV			270(7) ns	IT	128Cd	(5−)
128m2Cd	2714.6(4) keV			3.56(6) μs	IT	128Cd	(10+)
128m2Cd	4286.6(15) keV			6.3(8) ms	IT	128Cd	(15−)
129Cd	48	81	128.9322356(57)	147(3) ms	β− (?%)	129In	11/2−
					β−, n (?%)	128In
129m1Cd	343(8) keV			157(8) ms	β− (?%)	129In	3/2+
					β−, n (?%)	128In
129m2Cd	2283(8) keV			3.6(2) ms	IT	129Cd	(21/2+)
130Cd	48	82	129.934388(24)	126.8(18) ms	β− (96.5%)	130In	0+
					β−, n (3.5%)	129In
130mCd	2129.6(10) keV			240(16) ns	IT	130Cd	(8+)
131Cd	48	83	130.940728(21)	98(2) ms	β− (96.5%)	131In	7/2−#
					β−, n (3.5%)	130In
132Cd	48	84	131.945823(64)	84(5) ms	β−, n (60%)	131In	0+
					β− (40%)	132In
133Cd	48	85	132.95261(22)#	61(6) ms	β− (?%)	133In	7/2−#
					β−, n (?%)	132In
134Cd	48	86	133.95764(32)#	65(15) ms	β−	134In	0+
This table header & footer: view

1. ^mCd – 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. Bold half-life – nearly stable, half-life longer than age of universe.
5. Modes of decay:

   EC:	Electron capture
   IT:	Isomeric transition
   n:	Neutron emission
   p:	Proton emission

6. Bold italics symbol as daughter – Daughter product is nearly stable.
7. Bold symbol as daughter – Daughter product is stable.
8. ( ) spin value – Indicates spin with weak assignment arguments.
9. # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
10. Believed to decay by β⁺β⁺ to ¹⁰⁶Pd with a half-life over 1.1×10²¹ years
11. Believed to decay by β⁺β⁺ to ¹⁰⁸Pd with a half-life over 4.1×10¹⁷ years
12. Fission product
13. Primordial radionuclide
14. Believed to undergo β⁻β⁻ decay to ¹¹⁴Sn with a half-life over 9.2×10¹⁶ years

Cadmium-113m

Medium-lived fission products

• v
• t
• e

Nuclide	t1⁄2	Yield	Q[a 1]	βγ
	(a)	(%)[a 2]	(keV)
155Eu	4.74	0.0803[a 3]	252	βγ
85Kr	10.73	0.2180[a 4]	687	βγ
113mCd	13.9	0.0008[a 3]	316	β
90Sr	28.91	4.505	2826[a 5]	β
137Cs	30.04	6.337	1176	βγ
121mSn	43.9	0.00005	390	βγ
151Sm	94.6	0.5314[a 3]	77	β
Decay energy is split among β, neutrino, and γ if any. Per 65 thermal neutron fissions of 235U and 35 of 239Pu. Neutron poison; in thermal reactors most is destroyed by further neutron capture. Less than 1/4 of mass-85 fission products as most bypass ground state: Br-85 -> Kr-85m -> Rb-85. Has decay energy 546 keV; its decay product Y-90 has decay energy 2.28 MeV with weak gamma branching.

Cadmium-113m is a cadmium radioisotope and nuclear isomer with a half-life of 13.9 years. In a normal thermal reactor, it has a very low fission product yield, plus its large neutron capture cross section means that most of even the small amount produced is destroyed in the course of the nuclear fuel's burnup; thus, this isotope is not a significant contributor to nuclear waste.

Fast fission or fission of some heavier actinides^[which?] will produce ^113mCd at higher yields.

See also

Daughter products other than cadmium

• Isotopes of tin
• Isotopes of indium
• Isotopes of silver
• Isotopes of palladium
• Isotopes of rhodium