Rotational Magnetic Moments of Lithium Hydride and Deuteride

Abstract

Resonances of the rotational magnetic moments were observed in molecular beams of lithium hydride and lithium deuteride. The shape of the LiH rotational magnetic resonance curve was observed to be asymmetric and the width of the curve was observed to increase with increasing magnetic field. These effects were ascribed to centrifugal stretching causing the magnetic moment per unit of angular momentum to vary with angular momentum. The variation was assumed to be of the form, $\frac{{\mu }_R}{J}=g_0+CJ(J+1\mathrm{})\mathrm{}$, where ${\mu }_R$ is the rotational magnetic moment and $J$ is the quantum number of the total rotational angular momentum. The values of the constants $g_0$ and $C$ assigned to LiH were: $g_0=-0.654\mathrm{}\pm 0.007$ nuclear magneton and $C=(1.2\mathrm{}\pm 0.6)\times {10}^{-4\mathrm{}}$ nuclear magneton. For LiD, these constants were found to be: $g_0=-0.272\mathrm{}\pm 0.005$ nuclear magneton and $C=(3.4\mathrm{}\pm 1.7)\times {10}^{-5\mathrm{}}$ nuclear magneton. The electric dipole moment and its polarity were calculated from the rotational magnetic moments of LiH and LiD. The results of this calculation were ${\mu }_e=5.9\mathrm{}\pm 0.5$ debyes with the polarity ${\mathrm{Li}}^{+}$ ${\mathrm{H}}^{-}$. The magnitude of the rotational magnetic moment resonance signals suggest the occurrence of multiple-quantum transitions, which may make possible the observation of rotational magnetic moment resonances in other molecules, even if the rotational gyromagnetic ratios are quite small.