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 6.50 h ε 107Ag
108Cd0.89%stable
109Cdsynth461.3 dε 109Ag
110Cd12.5%stable
111Cd12.8%stable
112Cd24.1%stable
113Cd12.2%8.04×1015 y β 113In
113mCdsynth13.9 yβ113In
IT 113Cd
114Cd28.8%stable
115Cdsynth53.46 hβ 115In
116Cd7.51%2.69×1019 yββ 116Sn
Standard atomic weight Ar°(Cd)

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 7 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 (t1/2 13.9 years), 115mCd (t1/2 44.6 days) and 117mCd (t1/2 3.44 hours).

Contents

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
94Cd484693.95659(54)#80# ms
[> 760 ns]
0+
95Cd484794.94948(61)#32(3) ms β+ (95.4%)95Ag9/2+#
β+, p (4.6%)94Pd
96Cd484895.94034(44)#1.003(47) sβ+ (98.4%)96Ag0+
β+, p (1.6%)95Pd
96m1Cd6000(1400) keV511(26) msβ+ (84.6%)96Ag16+
β+, p (15.4%)95Pd
96m2Cd5605(5) keV198(18) ns IT 96Cd(12−,13−)
97Cd484996.93480(45)1.16(5) sβ+ (92.6%)97Ag(9/2+)
β+, p (7.4%)96Pd
97m1Cd1245.1(2) keV730(70) μsIT97Cd(1/2−)
97m2Cd2620(580) keV3.86(6) sβ+ (74.9%)97Ag(25/2+)
β+, p (25.1%)96Pd
98Cd485097.927389(56)9.29(10) sβ+ (>99.97%)98Ag0+
β+, p (<0.029%)97Pd
98m1Cd2428.3(4) keV154(16) nsIT98Cd(8+)
98m2Cd6635(2) keV224(5) nsIT98Cd(12+)
99Cd485198.9249258(17)17(1) sβ+ (99.79%)99Ag5/2+#
β+, p (0.21%)98Pd
β+, α (<10−4%)95Rh
100Cd485299.9203488(18)49.1(5) sβ+100Ag0+
101Cd4853100.9185862(16)1.36(5) minβ+101Ag5/2+
102Cd4854101.9144818(18)5.5(5) minβ+102Ag0+
103Cd4855102.9134169(19)7.3(1) minβ+103Ag5/2+
104Cd4856103.9098562(18)57.7(10) minβ+104Ag0+
105Cd4857104.9094639(15)55.5(4) minβ+105Ag5/2+
105mCd2517.6(5) keV4.5(5) μsIT105Cd(21/2+)
106Cd4858105.9064598(12) Observationally stable [n 10] 0+0.01245(22)
107Cd4859106.9066120(18)6.50(2) hβ+107Ag5/2+
108Cd4860107.9041836(12)Observationally stable [n 11] 0+0.00888(11)
109Cd4861108.9049867(16)461.3(5) d EC 109Ag5/2+
109m1Cd59.60(7) keV11.8(16) μsIT109Cd1/2+
109m2Cd463.10(11) keV10.6(4) μsIT109Cd11/2−
110Cd4862109.90300747(41)Stable0+0.12470(61)
111Cd [n 12] 4863110.90418378(38)Stable1/2+0.12795(12)
111mCd396.214(21) keV48.50(9) minIT111Cd11/2−
112Cd [n 12] 4864111.90276390(27)Stable0+0.24109(7)
113Cd [n 12] [n 13] 4865112.90440811(26)8.04(5)×1015 yβ113In1/2+0.12227(7)
113mCd [n 12] 263.54(3) keV13.89(11) yβ (99.90%)113In11/2−
IT (0.0964%)113Cd
114Cd [n 12] 4866113.90336500(30)Observationally stable [n 14] 0+0.28754(81)
115Cd [n 12] 4867114.90543743(70)53.46(5) hβ115mIn1/2+
115mCd [n 12] 181.0(5) keV44.56(24) dβ115In11/2−
116Cd [n 12] [n 13] 4868115.90476323(17)2.69(9)×1019 yββ116Sn0+0.07512(54)
117Cd4869116.9072260(11)2.503(5) hβ117In1/2+
117mCd136.4(2) keV3.441(9) hβ117In11/2−
118Cd4870117.906922(21)50.3(2) minβ118In0+
119Cd4871118.909847(40)2.69(2) minβ119In1/2+
119mCd146.54(11) keV2.20(2) minβ119In11/2−
120Cd4872119.9098681(40)50.80(21) sβ120In0+
121Cd4873120.9129637(21)13.5(3) sβ121In3/2+
121mCd214.86(15) keV8.3(8) sβ121In11/2−
122Cd4874121.9134591(25)5.98(10) s [6] β122In0+
123Cd4875122.9168925(29)2.10(2) sβ123In3/2+
123mCd143(4) keV1.82(3) sβ (?%)123In11/2−
IT (?%)123Cd
124Cd4876123.9176598(28)1.25(2) sβ124In0+
125Cd4877124.9212576(31)680(40) msβ125In3/2+
125m1Cd186(4) keV480(30) msβ125In11/2−
125m2Cd1648(4) keV19(3) μsIT125Cd(19/2+)
126Cd4878125.9224303(25)512(5) msβ126In0+
127Cd4879126.9262033(67)480(100) msβ127In3/2+
127m1Cd285(8) keV360(40) msβ127In11/2−
127m2Cd1845(8) keV17.5(3) μsIT127Cd(19/2+)
128Cd4880127.9278168(69)246(2) msβ128In0+
128m1Cd1870.5(3) keV270(7) nsIT128Cd(5−)
128m2Cd2714.6(4) keV3.56(6) μsIT128Cd(10+)
128m2Cd4286.6(15) keV6.3(8) msIT128Cd(15−)
129Cd4881128.9322356(57)147(3) msβ (?%)129In11/2−
β, n (?%)128In
129m1Cd343(8) keV157(8) msβ (?%)129In3/2+
β, n (?%)128In
129m2Cd2283(8) keV3.6(2) msIT129Cd(21/2+)
130Cd4882129.934388(24)126.8(18) msβ (96.5%)130In0+
β, n (3.5%)129In
130mCd2129.6(10) keV240(16) nsIT130Cd(8+)
131Cd4883130.940728(21)98(2) msβ (96.5%)131In7/2−#
β, n (3.5%)130In
132Cd4884131.945823(64)84(5) msβ, n (60%)131In0+
β (40%)132In
133Cd4885132.95261(22)#61(6) msβ (?%)133In7/2−#
β, n (?%)132In
134Cd4886133.95764(32)#65(15) msβ134In0+
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 1.1×1021 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 8 Fission product
  13. 1 2 Primordial radionuclide
  14. Believed to undergo ββ decay to 114Sn with a half-life over 9.2×1016 years

Cadmium-113m

Nuclide t12 Yield Q [a 1] βγ
(a)(%) [a 2] (keV)
155Eu 4.740.0803 [a 3] 252βγ
85Kr 10.730.2180 [a 4] 687βγ
113mCd 13.90.0008 [a 3] 316β
90Sr 28.914.5052826 [a 5] β
137Cs 30.046.3371176βγ
121mSn 43.90.00005390βγ
151Sm 94.60.5314 [a 3] 77β
  1. Decay energy is split among β, neutrino, and γ if any.
  2. Per 65 thermal neutron fissions of 235U and 35 of 239Pu.
  3. 1 2 3 Neutron poison; in thermal reactors most is destroyed by further neutron capture.
  4. Less than 1/4 of mass-85 fission products as most bypass ground state: Br-85 -> Kr-85m -> Rb-85.
  5. 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

References

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