Molecular beam observations have been made of the radio-frequency resonance spectra corresponding to reorientations of the rotational magnetic moment in hydrogen and deuterium molecules. For deuterium in the state $I=J=1\mathrm{}$, these observations were made in magnetic fields of approximately 1800, 3500, and 5100 gauss. The direct result of these experiments is that the rotational magnetic moment of the deuterium molecule in the zeroth vibrational and first rotational states is ${}_0{}^{}{}_{}{}^{}{}_{}{}^{\mathrm{D}}{}_{}{}^{}〈{\mu }_R〉_1^{}{}_{}{}^{}=0.442884\mathrm{}\pm 0.000052$ nuclear magneton, and the dependence of diamagnetic susceptibility on molecular orientation is $({\xi }_{\pm 1}-{\xi }_0)=-(3.50\mathrm{}\pm 0.40)\times {10}^{-31\mathrm{}}$ erg ${\mathrm{gauss}}^{-2\mathrm{}}$ ${\mathrm{molecule}}^{-1\mathrm{}}$. Combining these values with the recent theory of Ramsey on zero-point vibration and centrifugal stretching in molecules leads to an improved evaluation of the molecular susceptibility and quadrupole moment of the electron distribution. The experiments also provide a check on the values of the spin-rotational and spin-spin interaction parameters previously obtained from observations of the resonance spectrum corresponding to reorientations of the total nuclear spin.

The observations for hydrogen in the state $I=0\mathrm{}$, $J=2\mathrm{}$ were made in magnetic fields of approximately 1800 gauss. The direct result of these experiments is that the rotational magnetic moment of the hydrogen molecule in the zeroth vibrational and second rotational states is ${}_0{}^{}{}_{}{}^{}{}_{}{}^{\mathrm{H}}{}_{}{}^{}〈\frac{{\mu }_R}{J}〉_2^{}{}_{}{}^{}=0.882265\mathrm{}\pm 0.000035$ nuclear magneton. This value in combination with the known value of 0.88291±0.00007 nuclear magneton for the first rotational state provides an independent check on the theory of zero-point vibration and centrifugal stretching in molecules and leads to an improved evaluation of the hydrogen molecular susceptibility.

• Received 15 February 1954

DOI:https://doi.org/10.1103/PhysRev.94.893