Column Descriptions

                                                                         
             Relative           Isotopic      Standard                   
Isotope      Atomic Mass        Composition   Atomic Weight    Notes     
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2   He  3    3.0160293201(25)   0.00000134(3)  4.002602(2)      g,r
        4    4.00260325413(6)   0.99999866(3)
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