Molecular Zeeman effect, electric dipole moment, and boron nuclear hyperfine coupling constants in HBS

The zero‐field microwave spectra of the J =0 → J = 1 transitions in H¹¹B³²S, D¹¹B³²S, and D¹⁰B³²S have been observed under high resolution to give the boron nuclear quadrupole coupling constants of eqQ = −3.72±0.03 MHz for ¹¹B and eqQ = −7.91±0.03 MHz for ¹⁰B and the nuclear magnetic spin rotation constants along the axis perpendicular to the internuclear axis of $M_{\perp }\text{=−7.2 ± 3.0\hspace{0.17em}}\mathrm{kHz}$ for ¹¹B and 1$M_{\perp }\text{=−2.6 ± 1.0\hspace{0.17em}}\mathrm{kHz}$ for ¹⁰B. The magnitude of the electric dipole moment was measured by high electric fields (Stark effect) to give |μ| = 1.298 ± 0.005 D. High magnetic fields (Zeeman effect) were used to measure the molecular g values and magnetic susceptibility anisotropies. The results are $g_{\perp }\text{=−0.0414 ± 0.0002}$ and ${\chi }_{\perp }{\mathrm{-\chi }}_{\parallel }{\text{=7.2 ± 0.5 × 10}}^{\text{−6}}\hspace{0.17em}{\mathrm{erg/G}}^2·\mathrm{mole}$ for H¹¹B³²S and $g_{\perp }\text{=−0.0356 ± 0.0002}$ and ${\chi }_{\perp }{\mathrm{-\chi }}_{\parallel }{\text{=9.8 ± 2.1 × 10}}^{\text{−6}}\hspace{0.17em}{\mathrm{erg/G}}^2·\mathrm{mole}$ for D¹¹B³²S. The resultant molecular electric quadrupole moment is Q_∥ =2.7±0.6 × 10⁻²⁶ esu · cm² and the g values from the H¹¹B³²S–D¹¹B³²S isotopic pair were used to determine the sign of the electric dipole moment, + HBS −.