Isotopes of cadmium

Naturally occurring cadmium (Cd) is composed of 8 isotopes. For two of them, natural radioactivity was observed, and three others are predicted to be radioactive but their decays were never observed, due to extremely long half-life times. The two natural radioactive isotopes are ¹¹³Cd (beta decay, half-life is 7.7 × 10¹⁵ years) and ¹¹⁶Cd (two-neutrino double beta decay, half-life is 2.9 × 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. At least three isotopes - ¹¹⁰Cd, ¹¹¹Cd, and ¹¹²Cd - are absolutely stable (except, theoretically, to spontaneous fission). Among the isotopes absent in the 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 8 known meta states with the most stable being ^113mCd (t_½ 14.1 years), ^115mCd (t_½ 44.6 days) and ^117mCd (t_½ 3.36 hours).

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).
Standard atomic mass: 112.411(8) u

Contents 1 Cadmium-113m 2 Table 2.1 Notes 3 References

Cadmium-113m

Medium-lived
fission products

Prop: Unit:	t½ a	Yield %	Q * keV	βγ *
155Eu	4.76	.0803	252	βγ
85Kr	10.76	.2180	687	βγ
113mCd	14.1	.0008	316	β
90Sr	28.9	4.505	2826	β
137Cs	30.23	6.337	1176	βγ
121mSn	43.9	.00005	390	βγ
151Sm	90	.5314	77	β

Cadmium-113m is a Cadmium radioisotope and nuclear isomer with a halflife 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 will produce ^113mCd at higher yields.

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life[n 1]	decay mode(s)[1][n 2]	daughter isotope(s)[n 3]	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
	excitation energy
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%)	94Rh
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 4]			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 5]			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)	Observationally Stable[n 6]			0+	0.1249(18)
111Cd[n 7]	48	63	110.9041781(29)	Observationally Stable[n 6]			1/2+	0.1280(12)
111mCd	396.214(21) keV			48.50(9) min	IT	111Cd	11/2-
112Cd[n 7]	48	64	111.9027578(29)	Observationally Stable[n 6]			0+	0.2413(21)
113Cd[n 8][n 7]	48	65	112.9044017(29)	7.7(3)×1015 a	β-	113In	1/2+	0.1222(12)
113mCd[n 7]	263.54(3) keV			14.1(5) a	β- (99.86%)	113In	11/2-
					IT (.139%)	113Cd
114Cd[n 7]	48	66	113.9033585(29)	Observationally Stable[n 9]			0+	0.2873(42)
115Cd[n 7]	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 8][n 7]	48	68	115.904756(3)	3.1(4)×1019 a	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	23Cd
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+

1. ^ Bold for isotopes with half-lives longer than the age of the universe (nearly stable)
2. ^ Abbreviations:
   EC: Electron capture
   IT: Isomeric transition
3. ^ Bold for stable isotopes, bold italics for nearly-stable isotopes (half-life longer than the age of the universe)
4. ^ Believed to decay by β⁺β⁺ to ¹⁰⁶Pd with a half-life over 410×10¹⁸ years
5. ^ Believed to decay by β⁺β⁺ to ¹⁰⁸Pd with a half-life over 410×10¹⁵ years
6. ^ ^{a b c} Theoretically capable of spontaneous fission
7. ^ ^{a b c d e f g} Fission product
8. ^ ^{a b} Primordial radionuclide
9. ^ Believed to undergo β^-β^- decay to ¹¹⁴Sn with a half-life over 6.4×10¹⁸ years

Notes

• The precision of the isotope abundances and atomic mass is limited through variations. The given ranges should be applicable to any normal terrestrial material.
• 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:
  • G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (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. http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf. 
• Isotopic compositions and standard atomic masses from:
  • J. R. de Laeter, J. K. Böhlke, P. De Bièvre, H. Hidaka, H. S. Peiser, K. J. R. Rosman and P. D. P. Taylor (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry 75 (6): 683–800. doi:10.1351/pac200375060683. http://www.iupac.org/publications/pac/75/6/0683/pdf/. 
  • M. E. Wieser (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry 78 (11): 2051–2066. doi:10.1351/pac200678112051. http://iupac.org/publications/pac/78/11/2051/pdf/. Lay summary. 
• Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
  • G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (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. http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf. 
  • National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. http://www.nndc.bnl.gov/nudat2/. Retrieved September 2005. 
  • N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide. CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0849304859. 

1. ^ http://www.nucleonica.net/unc.aspx

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