Precise atomic masses and mass differences for W and Re

The 1 m radius, second order double focusing mass spectrometer at the University of Manitoba has been used to obtain atomic mass differences for eleven mass doublets. These data are combined with well known values for the atomic masses of 13C, l6O, 35Cl, and 37Cl to derive both atomic masses and mass differences for all of the naturally-occurring isotopes of W and Re.