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The Isotopic Weight of H 2

1932; American Institute of Physics; Volume: 42; Issue: 1 Linguagem: Inglês

10.1103/physrev.42.1

1536-6065

Kenneth T. Bainbridge,

Quantum, superfluid, helium dynamics

The mass of neutral ${\mathrm{H}}^{2}$ was measured on a mass-spectrograph as 2.01351\ifmmode\pm\else\textpm\fi{}0.00006 referred to He and 2.01351\ifmmode\pm\else\textpm\fi{}0.00018 referred to ${\mathrm{O}}^{16}$=16. The equivalent packing fraction of ${\mathrm{H}}^{2}$ is 67.5 parts in 10,000. On the assumption that the nucleus is composed of two protons and one electron the energy of binding is approximately 2\ifmmode\times\else\texttimes\fi{}${10}^{6}$ electron-volts. If the ${\mathrm{H}}^{2}$ nucleus is made up of one proton and one Chadwick neutron of mass 1.0067 then the binding energy of these two particles is 9.7\ifmmode\times\else\texttimes\fi{}${10}^{5}$ electron-volts. ${\mathrm{H}}_{3}^{1+}$ and ${\mathrm{He}}^{+}$ provided the dispersion measurements for the spectra. The presence of ${\mathrm{H}}^{1}$ ${\mathrm{H}}^{2+}$ can only introduce in the mass determination a possible maximum error of 0.00003 mass units. Lines of mass 4.02852 on the spectra were attributed to ${\mathrm{H}}_{2}^{1}$ ${\mathrm{H}}^{2}$ ions because: (1) no lines of comparable intensity appeared in this position when commercial hydrogen of low ${\mathrm{H}}^{2}$ content was used; (2) under the conditions existing in the discharge tube the abundance of ${\mathrm{H}}_{2}^{2+}$ was negligibly small compared to the abundance of ${\mathrm{H}}_{2}^{1}$ ${\mathrm{H}}^{2+}$; (3) the mass is less than the mass of ${\mathrm{H}}_{4}^{1+}$ by an amount outside of the limits of error. Two samples of enriched hydrogen were used which had been prepared by Brickwedde; both had been tested spectroscopically by Urey and Murphy, and one of them was identical with Bleakney's Sample III. From the value for the mass of ${\mathrm{H}}^{2}$, the energy balance is calculated for one process of noncapture disintegration of ${\mathrm{N}}^{14}$ by neutron impact, suggested by Feather, which would result in ${\mathrm{C}}^{12}$ and ${\mathrm{H}}^{2}$. It is concluded that this disintegration could not possibly occur under the conditions of his experiments.