Isotopes of cadmium

Naturally occurring cadmium (₄₈Cd) is composed of 8 isotopes. For two of them, natural radioactivity was observed, and three others are predicted to be radioactive but their decays have not been observed, due to extremely long half-lives. The two natural radioactive isotopes are ¹¹³Cd (beta decay, half-life is 8.04 × 10¹⁵ years) and ¹¹⁶Cd (two-neutrino double beta decay, half-life is 2.8 × 10¹⁹ years). The other three are ¹⁰⁶Cd, ¹⁰⁸Cd (double electron capture), and ¹¹⁴Cd (double beta decay); only lower limits on their half-life times have been set. Three isotopes—¹¹⁰Cd, ¹¹¹Cd, and ¹¹²Cd—are theoretically stable. Among the isotopes absent in natural cadmium, the most long-lived are ¹⁰⁹Cd with a half-life of 462.6 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 have half-lives that are less than 5 minutes. This element also has 12 known meta states, with the most stable being ^113mCd (t_1/2 14.1 years), ^115mCd (t_1/2 44.6 days) and ^117mCd (t_1/2 3.36 hours).

Isotopes of cadmium (₄₈Cd)

Main isotopes[1] Decay abun­dance half-life (t1/2) mode pro­duct 106Cd 1.25% stable 107Cd synth 6.5 h ε 107Ag 108Cd 0.89% stable 109Cd synth 462.6 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 14.1 y β− 113In IT 113Cd 114Cd 28.8% stable 115Cd synth 53.46 h β− 115In 116Cd 7.51% 2.8×1019 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 in atomic mass from 94.950 u (⁹⁵Cd) to 131.946 u (¹³²Cd). The primary decay mode before the second most abundant stable isotope, ¹¹²Cd, is electron capture and the primary modes after are beta emission and electron capture. The primary decay product before ¹¹²Cd is element 47 (silver) and the primary product after is element 49 (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) [n 2][n 3]	Half-life [n 4]	Decay mode [n 5]	Daughter isotope [n 6][n 7]	Spin and parity [n 8][n 9]	Natural abundance (mole fraction)
	Excitation energy[n 9]							Normal proportion	Range of variation
95Cd	48	47	94.94987(64)#	5# ms			9/2+#
96Cd	48	48	95.93977(54)#	1# s	β+	96Ag	0+
97Cd	48	49	96.93494(43)#	2.8(6) s	β+ (>99.9%)	97Ag	9/2+#
					β+, p (<.1%)	96Pd
98Cd	48	50	97.92740(8)	9.2(3) s	β+ (99.975%)	98Ag	0+
					β+, p (.025%)	97Ag
98mCd	2427.5(6) keV			190(20) ns			8+#
99Cd	48	51	98.92501(22)#	16(3) s	β+ (99.78%)	99Ag	(5/2+)
					β+, p (.21%)	98Pd
					β+, α (10−4%)	95Rh
100Cd	48	52	99.92029(10)	49.1(5) s	β+	100Ag	0+
101Cd	48	53	100.91868(16)	1.36(5) min	β+	101Ag	(5/2+)
102Cd	48	54	101.91446(3)	5.5(5) min	β+	102Ag	0+
103Cd	48	55	102.913419(17)	7.3(1) min	β+	103Ag	5/2+
104Cd	48	56	103.909849(10)	57.7(10) min	β+	104Ag	0+
105Cd	48	57	104.909468(12)	55.5(4) min	β+	105Ag	5/2+
106Cd	48	58	105.906459(6)	Observationally Stable[n 10]			0+	0.0125(6)
107Cd	48	59	106.906618(6)	6.50(2) h	β+	107mAg	5/2+
108Cd	48	60	107.904184(6)	Observationally Stable[n 11]			0+	0.0089(3)
109Cd	48	61	108.904982(4)	461.4(12) d	EC	109Ag	5/2+
109m1Cd	59.6(4) keV			12(2) μs			1/2+
109m2Cd	463.0(5) keV			10.9(5) μs			11/2
110Cd	48	62	109.9030021(29)	Stable			0+	0.1249(18)
111Cd[n 12]	48	63	110.9041781(29)	Stable			1/2+	0.1280(12)
111mCd	396.214(21) keV			48.50(9) min	IT	111Cd	11/2−
112Cd[n 12]	48	64	111.9027578(29)	Stable			0+	0.2413(21)
113Cd[n 12][n 13]	48	65	112.9044017(29)	8.04(5)×1015 y	β−	113In	1/2+	0.1222(12)
113mCd[n 12]	263.54(3) keV			14.1(5) y	β− (99.86%)	113In	11/2−
					IT (.139%)	113Cd
114Cd[n 12]	48	66	113.9033585(29)	Observationally Stable[n 14]			0+	0.2873(42)
115Cd[n 12]	48	67	114.9054310(29)	53.46(5) h	β−	115mIn	1/2+
115mCd	181.0(5) keV			44.56(24) d	β−	115mIn	(11/2)−
116Cd[n 12][n 13]	48	68	115.904756(3)	2.8(2)×1019 y	β−β−	116Sn	0+	0.0749(18)
117Cd	48	69	116.907219(4)	2.49(4) h	β−	117mIn	1/2+
117mCd	136.4(2) keV			3.36(5) h	β−	117mIn	(11/2)−
118Cd	48	70	117.906915(22)	50.3(2) min	β−	118In	0+
119Cd	48	71	118.90992(9)	2.69(2) min	β−	119mIn	(3/2+)
119mCd	146.54(11) keV			2.20(2) min	β−	119mIn	(11/2−)#
120Cd	48	72	119.90985(2)	50.80(21) s	β−	120In	0+
121Cd	48	73	120.91298(9)	13.5(3) s	β−	121mIn	(3/2+)
121mCd	214.86(15) keV			8.3(8) s	β−	121mIn	(11/2−)
122Cd	48	74	121.91333(5)	5.24(3) s	β−	122In	0+
123Cd	48	75	122.91700(4)	2.10(2) s	β−	123mIn	(3/2)+
123mCd	316.52(23) keV			1.82(3) s	β−	123In	(11/2−)
					IT	123Cd
124Cd	48	76	123.91765(7)	1.25(2) s	β−	124In	0+
125Cd	48	77	124.92125(7)	0.65(2) s	β−	125mIn	(3/2+)#
125mCd	50(70) keV			570(90) ms	β−	125In	11/2−#
126Cd	48	78	125.92235(6)	0.515(17) s	β−	126In	0+
127Cd	48	79	126.92644(8)	0.37(7) s	β−	127mIn	(3/2+)
128Cd	48	80	127.92776(32)	0.28(4) s	β−	128In	0+
129Cd	48	81	128.93215(32)#	242(8) ms	β− (>99.9%)	129In	3/2+#
					IT (<.1%)	129Cd
129mCd	0(200)# keV			104(6) ms			11/2−#
130Cd	48	82	129.9339(3)	162(7) ms	β− (96%)	130In	0+
					β−, n (4%)	129In
131Cd	48	83	130.94067(32)#	68(3) ms			7/2−#
132Cd	48	84	131.94555(54)#	97(10) ms			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 4.1×10²⁰ 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 6.4×10¹⁸ years

• Hyperdeformation is predicted to be found in ¹⁰⁷Cd.

Cadmium-113m

Medium-lived
fission products

	t½ (year)	Yield (%)	Q (keV)	βγ
155Eu	4.76	0.0803	252	βγ
85Kr	10.76	0.2180	687	βγ
113mCd	14.1	0.0008	316	β
90Sr	28.9	4.505	2826	β
137Cs	30.23	6.337	1176	βγ
121mSn	43.9	0.00005	390	βγ
151Sm	88.8	0.5314	77	β

Cadmium-113m is a cadmium radioisotope and nuclear isomer with a half-life of 14.1 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.

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: Cadmium". CIAAW. 2013.
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. Ratié, Gildas; Chrastný, Vladislav; Guinoiseau, Damien; Marsac, Rémi; Vaňková, Zuzana; Komárek, Michael (2021-06-01). "Cadmium Isotope Fractionation during Complexation with Humic Acid". Environmental Science & Technology. 55 (11): 7430–7444. Bibcode:2021EnST...55.7430R. doi:10.1021/acs.est.1c00646. ISSN 0013-936X. PMID 33970606. S2CID 234361430.

• Isotope masses from:
  • Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
• Isotopic compositions and standard atomic masses from:
  • de Laeter, John Robert; Böhlke, John Karl; De Bièvre, Paul; Hidaka, Hiroshi; Peiser, H. Steffen; Rosman, Kevin J. R.; Taylor, Philip D. P. (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
  • Wieser, Michael E. (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051.
• "News & Notices: Standard Atomic Weights Revised". International Union of Pure and Applied Chemistry. 19 October 2005.
• Half-life, spin, and isomer data selected from the following sources.
  • Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
  • National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
  • Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.