Nuclear Magnetic Interactions in Hydrogen Fluoride

The radio-frequency spectra corresponding to the reorientation of the proton and fluorine nuclear magnetic moments in hydrogen fluoride (HF) have been observed in fields of 900, 1800, and 3600 gauss by means of the molecular beam resonance method. Details are presented on the design and construction of the new molecular beam apparatus and electron-bombardment detector used in the experiment. The theory of the HF strong-field energy levels is outlined, and the expected proton and fluorine transitions derived for $J=0, 1, \mathrm{and} 2$ are tabulated. From the observed resonance shapes, one can deduce the magnitudes of the spin-rotational interactions of the proton and fluorine nuclei, and their spin-spin interaction. These are: $\left|c_p\right|=71\mathrm{}\pm 3$ kc/sec, $\left|c_{\mathrm{F}}\right|=305\mathrm{}\pm 2$ kc/sec, $d_1=57\mathrm{}\pm 2$ kc/sec. The correctness of these parameters was checked by the good agreement between the experimental curves and resonance shapes predicted by Univac programs using these values. The observed fluorine spin-rotational interaction constant is the largest yet observed and corresponds to a rotational magnetic field at the nucleus of 76 gauss per unit rotational quantum number. The implications of the large spin-rotational interaction for relaxation processes in nuclear magnetic resonance experiments are discussed.