The Mass Differences of the Fundamental Doublets Used in the Determination of the Isotopic WeightsC12andN14

Abstract

The values of the mass of ${\mathrm{C}}^{12}$ as determined by different observers, show a discrepancy well outside the corresponding probable errors. This mass is important since it is used in the determination of so many of the other isotopic weights. Fundamental to its determination is the mass difference ${\mathrm{C}}^{12}$ ${\mathrm{H}}_4$—${\mathrm{O}}^{16}$. With the large spectrograph completed last year, a new determination of this mass difference has been made. In addition, the ${\mathrm{C}}^{12}$ ${\mathrm{H}}_2$—${\mathrm{N}}^{14}$ mass difference has been checked by means of the doublets ${\mathrm{C}}^{12}$ ${\mathrm{H}}_3$—${\mathrm{N}}^{14}$H and ${\mathrm{C}}^{12}$ ${\mathrm{H}}_4$—${\mathrm{N}}^{14}$ ${\mathrm{H}}_2$. These values together with the associated experiments are reported in the present paper.