Column Descriptions

                                                                         
             Relative           Isotopic      Standard                   
Isotope      Atomic Mass        Composition   Atomic Weight    Notes     
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18  Ar  36   35.967545105(28)   0.003336(21)  39.948(1)        g,r
        38   37.96273211(21)    0.000629(7) 
        40   39.9623831237(24)  0.996035(25)
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