Masses of Light Atoms

Abstract

The mass differences of 33 doublets have been measured with a modified Bainbridge-Jordan type mass spectrograph, which has an experimental resolving power of about 60 000. In general, the values obtained are in good agreement with other mass spectroscopic data and with those calculated from nuclear disintegration energies. However, for the ${\mathrm{C}}^{12}$ ${\left({\mathrm{H}}^1\right)}_4$-${\mathrm{O}}^{16}$ doublet, the discrepancy between the present value 364.19±0.06 (×${10}^{-4\mathrm{}}$ amu) and the value 363.72±0.19 obtained from nuclear data does not seem to be negligible. The author calculated the atomic mass of ${\mathrm{C}}^{12}$, one of the mass substandards, from the four different doublet sets, one with the ${\mathrm{C}}^{12}$ ${\left({\mathrm{H}}^1\right)}_4$-${\mathrm{O}}^{16}$ doublet and the others without. The four values of the ${\mathrm{C}}^{12}$ mass obtained were found to be in good agreement with one another, and their weighted average, 12.003844±6, was adopted as the atomic mass of ${\mathrm{C}}^{12}$. Other mass substandards ${\mathrm{H}}^1$ and ${\mathrm{D}}^2$ were calculated from the (${\mathrm{H}}^1$); -${\mathrm{D}}^2$ doublet and the ${\left({\mathrm{D}}^2\right)}_3$-½${\mathrm{C}}^{12}$ doublet using the above ${\mathrm{C}}^{12}$ mass, and the atomic masses of ${\mathrm{H}}^1$ and ${\mathrm{D}}^2$ were obtained to be ${\mathrm{H}}^1$=1.008145±2, ${\mathrm{D}}^2$=2.014741±3. The atomic masses of other isotopes were determined by using these mass substandards.