ISOTOPIC COMPOSITIONS OF THE ELEMENTS 1997

The Commission's Subcommittee for the Isotopic Composition of the Elem ents (SIAM) has carried out its biennial review of isotopic compositio ns, as determined by mass spectrometry and other relevant methods. Thi s involves a critical evaluation of the published literature, element by element, and forms the basis of the Table of Isotopic Compositions of the Elements as Determined by Mass Spectrometry presented here. New guidelines have been used to arrive at the uncertainties on the isoto pic abundances and there are numerous changes to the Table since it wa s last published in 1991. Atomic Weights calculated from this table ar e consistent with (A) under bar(r)(E) values listed in the Table of St andard Atomic Weights 1997.