High-Resolution Measurements of 35Cl and D Quadrupole Coupling in CH2DCl and CD3Cl

Hyperfine structure on $\text{J=1→ 0}$ transitions in ${\mathrm{CH}}_2{\mathrm{D}}^{35}\mathrm{Cl}$ and ${\mathrm{CD}}_3^{35}\mathrm{Cl}$ was observed with a molecular‐beam maser spectrometer. Splittings arising from deuteron quadrupole coupling were completely resolved for some transitions and partially resolved in others. The ³⁵Cl quadrupole coupling along the $\mathrm{C}–\mathrm{Cl}$ bond direction was ${\mathrm{eq}}_{\mathrm{zz}}\text{Q=74\hspace{0.17em}687.3± 0.5\hspace{0.17em}}\mathrm{kHz}$ for CH₂DCl and ${\mathrm{eq}}_{\mathrm{zz}}\text{Q=74\hspace{0.17em}573.1± 0.5\hspace{0.17em}}\mathrm{kHz}$ for CD₃Cl. This is a difference of 0.15% for the ³⁵Cl quadrupole coupling in the $\mathrm{C}–\mathrm{Cl}$ bond direction. The average deuterium quadrupole coupling strength was ${\mathrm{eq}}_{\mathrm{zz}}\text{Q=170.8± 6.0\hspace{0.17em}}\mathrm{kHz}$ . Calculation of hyperfine structure due to four quadrupole nuclei, three of which are equivalent, is discussed.