Stark Effect and Hyperfine Structure of Hydrogen Fluoride

Abstract

The nuclear hyperfine structure constants and the electric dipole moment of hydrogen fluoride, ${\mathrm{H}}^1$ ${\mathrm{F}}^{19}$, in the ground-vibration and first excited rotation state have been measured in a molecular beam electric resonance experiment. The hfs constants are: $c_{\mathrm{F}}=307.6\mathrm{}\pm 1.5$ kc/sec, $c_p=-70.6\mathrm{}\pm 1.3$ kc/sec, $\frac{2}{5}\frac{g_p{g}_{\mathrm{F}}{{\mu }_{\mathrm{nm}}}^2}{h〈r^3〉}=57.6\mathrm{}\pm 0.44$ kc/sec. The apparatus was calibrated by observing Stark transitions in the ground-vibration and first excited rotation state of carbonyl sulfide, ${\mathrm{O}}^{16}$ ${\mathrm{C}}^{12}$ ${\mathrm{S}}^{32}$, which gave $\frac{{\mu }_{\mathrm{HF}}}{{\mu }_{\mathrm{OCS}}}=2.554\mathrm{}\pm 0.0037$, or ${\mu }_{\mathrm{HF}}=1.8195\mathrm{}\pm 0.0026$ D, by using ${\mu }_{\mathrm{OCS}}=0.7124\mathrm{}\pm 0.0002$ D. An absolute measurement of the OCS electric dipole moment gave ${\mu }_{\mathrm{OCS}}=0.7120\mathrm{}\pm 0.003$ D. A digitally computed solution of the Stark effect with magnetic hyperfine structure was necessary to interpret the data. The theory and experiment are in good agreement over the range of electric-field strengths used in the experiment. The hfs constants are in excellent agreement with the averaged absolute values of these constants as measured in a molecular beam magnetic resonance experiment. The agreement has significance because of discrepancies between the results from the two resonance methods, for some other molecules, in previous experiments.