Isotopes of cadmium

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Isotopes of cadmium  (48Cd)
Main isotopes [1] Decay
abun­dance half-life (t1/2) mode pro­duct
106Cd1.25% stable
107Cd synth 6.5 h ε 107Ag
108Cd0.89%stable
109Cdsynth462.6 dε 109Ag
110Cd12.5%stable
111Cd12.8%stable
112Cd24.1%stable
113Cd12.2%8.04×1015 y β 113In
113mCdsynth14.1 yβ113In
IT 113Cd
114Cd28.8%stable
115Cdsynth53.46 hβ 115In
116Cd7.51%2.8×1019 yββ 116Sn
Standard atomic weight Ar°(Cd)

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 (t1/2 14.1 years), 115mCd (t1/2 44.6 days) and 117mCd (t1/2 3.36 hours).

Contents

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 proportionRange of variation
95Cd484794.94987(64)#5# ms9/2+#
96Cd484895.93977(54)#1# s β+ 96Ag0+
97Cd484996.93494(43)#2.8(6) sβ+ (>99.9%)97Ag9/2+#
β+, p (<.1%)96Pd
98Cd485097.92740(8)9.2(3) sβ+ (99.975%)98Ag0+
β+, p (.025%)97Ag
98mCd2427.5(6) keV190(20) ns8+#
99Cd485198.92501(22)#16(3) sβ+ (99.78%)99Ag(5/2+)
β+, p (.21%)98Pd
β+, α (10−4%)95Rh
100Cd485299.92029(10)49.1(5) sβ+100Ag0+
101Cd4853100.91868(16)1.36(5) minβ+101Ag(5/2+)
102Cd4854101.91446(3)5.5(5) minβ+102Ag0+
103Cd4855102.913419(17)7.3(1) minβ+103Ag5/2+
104Cd4856103.909849(10)57.7(10) minβ+104Ag0+
105Cd4857104.909468(12)55.5(4) minβ+105Ag5/2+
106Cd4858105.906459(6) Observationally Stable [n 10] 0+0.0125(6)
107Cd4859106.906618(6)6.50(2) hβ+107mAg5/2+
108Cd4860107.904184(6)Observationally Stable [n 11] 0+0.0089(3)
109Cd4861108.904982(4)461.4(12) dEC109Ag5/2+
109m1Cd59.6(4) keV12(2) μs1/2+
109m2Cd463.0(5) keV10.9(5) μs11/2
110Cd4862109.9030021(29)Stable0+0.1249(18)
111Cd [n 12] 4863110.9041781(29)Stable1/2+0.1280(12)
111mCd396.214(21) keV48.50(9) minIT111Cd11/2−
112Cd [n 12] 4864111.9027578(29)Stable0+0.2413(21)
113Cd [n 12] [n 13] 4865112.9044017(29)8.04(5)×1015 yβ113In1/2+0.1222(12)
113mCd [n 12] 263.54(3) keV14.1(5) yβ (99.86%)113In11/2−
IT (.139%)113Cd
114Cd [n 12] 4866113.9033585(29)Observationally Stable [n 14] 0+0.2873(42)
115Cd [n 12] 4867114.9054310(29)53.46(5) hβ115mIn1/2+
115mCd181.0(5) keV44.56(24) dβ115mIn(11/2)−
116Cd [n 12] [n 13] 4868115.904756(3)2.8(2)×1019 yββ116Sn0+0.0749(18)
117Cd4869116.907219(4)2.49(4) hβ117mIn1/2+
117mCd136.4(2) keV3.36(5) hβ117mIn(11/2)−
118Cd4870117.906915(22)50.3(2) minβ118In0+
119Cd4871118.90992(9)2.69(2) minβ119mIn(3/2+)
119mCd146.54(11) keV2.20(2) minβ119mIn(11/2−)#
120Cd4872119.90985(2)50.80(21) sβ120In0+
121Cd4873120.91298(9)13.5(3) sβ121mIn(3/2+)
121mCd214.86(15) keV8.3(8) sβ121mIn(11/2−)
122Cd4874121.91333(5)5.24(3) sβ122In0+
123Cd4875122.91700(4)2.10(2) sβ123mIn(3/2)+
123mCd316.52(23) keV1.82(3) sβ123In(11/2−)
IT123Cd
124Cd4876123.91765(7)1.25(2) sβ124In0+
125Cd4877124.92125(7)0.65(2) sβ125mIn(3/2+)#
125mCd50(70) keV570(90) msβ125In11/2−#
126Cd4878125.92235(6)0.515(17) sβ126In0+
127Cd4879126.92644(8)0.37(7) sβ127mIn(3/2+)
128Cd4880127.92776(32)0.28(4) sβ128In0+
129Cd4881128.93215(32)#242(8) msβ (>99.9%)129In3/2+#
IT (<.1%)129Cd
129mCd0(200)# keV104(6) ms11/2−#
130Cd4882129.9339(3)162(7) msβ (96%)130In0+
β, n (4%)129In
131Cd4883130.94067(32)#68(3) ms7/2−#
132Cd4884131.94555(54)#97(10) ms0+
This table header & footer:
  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. 1 2 #  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. 1 2 3 4 5 6 7 Fission product
  13. 1 2 Primordial radionuclide
  14. Believed to undergo ββ decay to 114Sn with a half-life over 6.4×1018 years

Cadmium-113m

Medium-lived
fission products [ further explanation needed ]
t½
(year)
Yield
(%)
Q
(keV)
βγ
155Eu 4.760.0803252βγ
85Kr 10.760.2180687βγ
113mCd 14.10.0008316β
90Sr 28.94.5052826β
137Cs 30.236.3371176βγ
121mSn 43.90.00005390βγ
151Sm 88.80.531477β

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.

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References

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