Knowledge Bank

Stark-hyperfine spectra are obtained for the l10 and l11, rotational states of D2O using a molecular beam electric resonance spectrometer. Hyperfine constants and the electric dipole moments determined from the data are in general agreement with earlier results with the exception of an apparent confusion in the literature with regard to the axis system in which the components of the nuclear quadrupole coupling tensor are reported. As these components are often used in the structure determination of van der Waals complexes, inconsistencies have sometimes been observed. The rotational states measured in this study provide directly two of the tensor components in the principal inertial axis system of the molecule, namely $eQqbb=22.436(95)kHz$ and $eQqee=-175.027(22)kHz$, with the traceless character of the tensor providing the third. These components may be used to provide structural data for van der Waals complexes containing $D2O$ and resolve an inconsistency in the $N2-D2O$ molecule. Implications for other complexes will be discussed and comparison will be made with the quadrupole coupling tensor for HDO.