Measurement of the Molecular g Values in H2O and D2O and Hyperfine Structure in H2O

Individual components of the Zeeman transitions in the rotational spectrum of H₂O and D₂O were resolved in fields of 25–30 kG. This allowed determination of the $g$ values with greater accuracy than previous measurements. The $g$ values obtained for H₂O were ${\text{g(5}}_{23}\text{)\hspace{0.17em}=\hspace{0.17em}0.6959\hspace{0.17em}±\hspace{0.17em}0.001}$ and ${\text{g(6}}_{16}\text{)\hspace{0.17em}=\hspace{0.17em}0.6565\hspace{0.17em}±\hspace{0.17em}0.001}$ . The $g$ values obtained for D₂O were $g_{\mathrm{aa}}{\text{\hspace{0.17em}=\hspace{0.17em}0.3233\hspace{0.17em}±\hspace{0.17em}0.001, g}}_{\mathrm{bb}}\text{\hspace{0.17em}=\hspace{0.17em}0.3580\hspace{0.17em}±\hspace{0.17em}0.001,}\mathrm{and}{g}_{\mathrm{cc}}\text{\hspace{0.17em}=\hspace{0.17em}0.3226\hspace{0.17em}±\hspace{0.17em}0.001}$ . Analysis of the combined results indicates that the $g$ values for H₂O are positive and that the values are $g_{\mathrm{aa}}{\text{\hspace{0.17em}=\hspace{0.17em}0.6650\hspace{0.17em}±\hspace{0.17em}0.002, g}}_{\mathrm{bb}}\text{\hspace{0.17em}=\hspace{0.17em}0.7145\hspace{0.17em}±\hspace{0.17em}0.002}$ , and $g_{\mathrm{cc}}\text{\hspace{0.17em}=\hspace{0.17em}0.6465\hspace{0.17em}±\hspace{0.17em}0.002}$ . Hyperfine structure on the 6₁₆ − 5₂₃ transition in H₂O was observed in a maser spectrometer, and the spin–rotation and spin–spin coupling constants were obtained. The measured value of the rotational transition frequency was 22 235 079.85 ± 0.05 kHz. The magnetic susceptibility anisotropies and molecular quadrupole moments were determined in H₂O.