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Chapter 16: Selected Radioactive Isotopes

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    Decay modes are \(\alpha\), \(\beta^{-}\), \(\beta^{+}\), electron capture (EC) and isomeric transition (IT). EC results in the same daughter nucleus as would \(\beta^{+}\) decay. IT is a transition from a metastable excited state. Energies for \(\beta^{\pm}\) decays are the maxima; average energies are roughly one-half the maxima.

    Table \(\PageIndex{1}\): Selected Radioactive Isotopes
    Isotope t 1/2 DecayMode(s) Energy(MeV) Percent \(\gamma\)-Ray Energy(MeV) Percent
    \({ }^{3} \mathrm{H}\) 12.33 y \(\beta^{-}\) 0.0186 100%    
    \({ }^{14} \mathrm{C}\) 5730 y \(\beta^{-}\) 0.156 100%    
    \({ }^{13} \mathrm{N}\) 9.96 min \(\beta^{+}\) 1.20 100%    
    \({ }^{22} \mathrm{Na}\) 2.602 y \(\beta^{+}\) 0.55 90% \(\gamma\) 1.27 100%
    \({ }^{32} \mathrm{P}\) 14.28 d \(\beta^{-}\) 1.71 100%    
    \({ }^{35} \mathrm{S}\) 87.4 d \(\beta^{-}\) 0.167 100%    
    \({ }^{36} \mathrm{Cl}\) \(3.00 \times 10^{5} \mathrm{y}\) \(\beta^{-}\) 0.710 100%    
    \({ }^{40} \mathrm{K}\) \(1.28 \times 10^{9} \mathrm{y}\) \(\beta^{-}\) 1.31 89%    
    \({ }^{43} \mathrm{K}\) 22.3 h \(\beta^{-}\) 0.827 87% \(\gamma \mathrm{s}\) 0.373 87%
              0.618 87%
    \({ }^{45} \mathrm{Ca}\) 165 d \(\beta^{-}\) 0.257 100%    
    \({ }^{51} \mathrm{Cr}\) 27.70 d EC     \(\gamma\) 0.320 10%
    \({ }^{52} \mathrm{Mn}\) 5.59d \(\beta^{+}\) 3.69 28% \(\gamma \mathrm{s}\) 1.33 28%
              1.43 28%
    \({ }^{52} \mathrm{Fe}\) 8.27 h \(\beta^{+}\) 1.80 43% 0.169 43%
              0.378 43%
    \({ }^{59} \mathrm{Fe}\) 44.6 d \(\beta^{-} \mathrm{s}\) 0.273 45% \(\gamma \mathrm{s}\) 1.10 57%
          0.466 55% 1.29 43%
    \({ }^{60} \mathrm{Co}\) 5.271 y \(\beta^{-}\) 0.318 100% \(\gamma \mathrm{s}\) 1.17 100%
              1.33 100%
    \({ }^{65} \mathrm{Zn}\) 244.1 d EC     \(\gamma\) 1.12 51%
    \({ }^{67} \mathrm{Ga}\) 78.3 h EC     \(\gamma \mathrm{s}\) 0.0933 70%
              0.185 35%
              0.300 19%
              others  
    \({ }^{75} \mathrm{Se}\) 118.5 d EC     \(\gamma \mathrm{s}\) 0.121 20%
              0.136 65%
              0.265 68%
              0.280 20%
              others  
    \({ }^{86} \mathrm{Rb}\) 18.8 d \(\beta^{-} \mathrm{s}\) 0.69 9% \(\gamma\) 1.08 9%
          1.77 91%    
    \({ }^{85} \mathrm{Sr}\) 64.8 d EC     \(\gamma\) 0.514 100%
    \({ }^{90} \mathrm{Sr}\) 28.8 y \(\beta^{-}\) 0.546 100%    
    \({ }^{90} \mathrm{Y}\) 64.1 h \(\beta^{-}\) 2.28 100%    
    \({ }^{99 \mathrm{m}} \mathrm{Tc}\) 6.02 h IT     \(\gamma\) 0.142 100%
    \({ }^{113 \mathrm{m}} \mathrm{In}\) 99.5 min IT     \(\gamma\) 0.392 100%
    \({ }^{123} \mathrm{I}\) 13.0 h EC     \(\gamma\) 0.159 \(\approx 100 \%\)
    \({ }^{131} \mathrm{I}\) 8.040 d \(\beta^{-} \mathrm{s}\) 0.248 7% \(\gamma \mathrm{s}\) 0.364 85%
          0.607 93% others  
          others      
    \({ }^{129} \mathrm{Cs}\) 32.3 h EC     \(\gamma \mathrm{s}\) 0.0400 35%
              0.372 32%
              0.411 25%
              others  
    \({ }^{137} \mathrm{Cs}\) 30.17 y \(\beta^{-} \mathrm{s}\) ­ 0.511 95% \(\gamma\) 0.662 95%
          1.17 5%    
    \({ }^{140} \mathrm{Ba}\) 12.79 d \(\beta^{-}\) 1.035 \(\approx 100 \%\) \(\gamma \mathrm{s}\) 0.030 25%
              0.044 65%
              0.537 24%
              others  
    \({ }^{198} \mathrm{Au}\) 2.696 d \(\beta^{-}\) 1.161 \(\approx 100 \%\) \(\gamma\) 0.412 \(\approx 100 \%\)
    \({ }^{197} \mathrm{Hg}\) 64.1 h EC     \(\gamma\) 0.0733 100%
    \({ }^{210} \mathrm{Po}\) 138.38 d \(\alpha\) 5.41 100%    
    \({ }^{226} \mathrm{Ra}\) \(1.60 \times 10^{3} \mathrm{y}\) \(\alpha \mathrm{s}\) 4.68 5% \(\gamma\) 0.186 100%
          4.87 95%    
    \({ }^{235} \mathrm{U}\) \(7.038 \times 10^{8} \mathrm{y}\) \(\alpha\) 4.68 \(\approx 100 \%\) \(\gamma \mathrm{s}\) numerous <0.400%
    \({ }^{238} \mathrm{U}\) \(4.468 \times 10^{9} \mathrm{y}\) \(\alpha \mathrm{s}\) 4.22 23% \(\gamma\) 0.050 23%
          4.27 77%    
    \({ }^{237} \mathrm{Np}\) \(2.14 \times 10^{6} \mathrm{y}\) \(\alpha \mathrm{s}\) numerous   \(\gamma \mathrm{s}\) numerous <0.250%
          4.96 (max.)      
    \({ }^{239} \mathrm{Pu}\) \(2.41 \times 10^{4} \mathrm{y}\) \(\alpha \mathrm{s}\) 5.19 11% \(\gamma \mathrm{s}\) \(7.5 \times 10^{-5}\) 73%
          5.23 15% 0.013 15%
          5.24 73% 0.052 10%
              others  
    \({ }^{243} \mathrm{Am}\) \(7.37 \times 10^{3} \mathrm{y}\) \(\alpha \mathrm{s}\) Max. 5.44   \(\gamma \mathrm{s}\) 0.075  
          5.37 88% others  
          5.32 11%    
          others

    This page titled Chapter 16: Selected Radioactive Isotopes is shared under a CC BY 4.0 license and was authored, remixed, and/or curated by OpenStax.

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