Atomic Masses of H1, C12, and S32

Abstract

The Minnesota 16-inch double-focusing mass spectrometer has been used to measure a series of mass doublets which enable one to calculate the atomic masses of ${\mathrm{H}}^1$, ${\mathrm{C}}^{12}$, and ${\mathrm{S}}^{22}$. The doublet ½${\mathrm{C}}_4$ ${\mathrm{H}}_4$O—${\mathrm{H}}_2$ ${\mathrm{O}}_2$ is used to relate the ${\mathrm{C}}^{12}$ mass directly to that of the ${\mathrm{O}}^{16}$ standard. Recent tests of the instrument and its calibration give confidence in the reliability of the present results. The resulting mass values are ${\mathrm{H}}^1$ = 1.008 1451±2, ${\mathrm{C}}^{12}$ = 12.003 8156±4, and ${\mathrm{S}}^{32}$ = 31.982 2388±9 amu. These values differ from the previously reported results by more than the published errors might lead one to predict. However, in no cases do the changes reflect a significant change in previously published atomic masses.