Molecular-Beam Magnetic-Resonance Measurements of the Anisotropies of the Electric Polarizabilities ofH2andD2

Abstract

The anisotropies $\gamma ={\alpha }_{\parallel }-{\alpha }_{\perp }$ of the static electric polarizabilities of ${\mathrm{H}}_2$ and ${\mathrm{D}}_2$ were measured in a molecular-beam magnetic-resonance experiment. The quadratic Stark shifts of the separated-oscillatory-field resonances in the ground electronic and vibrational and $J=1\mathrm{}$ rotational states were measured in parallel electric and magnetic fields. The results are $\gamma \left({\mathrm{H}}_2\right)=0.3016\mathrm{}\pm .0005$ ${\mathrm{\AA }}^3$ and $\gamma \left({\mathrm{D}}_2\right)=0.2917\mathrm{}\pm .0004$ ${\mathrm{\AA }}^3$, which agree very closely with theory. A previously measured combination of the spin-rotation and quadrupole-interaction constants of ${\mathrm{D}}_2$ was independently remeasured, and the dependence upon orientation of the nuclear magnetic shielding of ${\mathrm{D}}_2$ was found to be ${\sigma }_{\pm 1}-{\sigma }_0=-11\mathrm{}\pm 9$ ppm. An efficient electron-bombardment detector was constructed for this experiment.