Microwave Stark Effect Measurement of the Dipole Moment and Polarizability of Carbonyl Sulfide

Abstract

An improved microwave spectrograph has been developed which permits measurements of electric field intensity to one part in ten thousand. The instrument is employed to make precise Stark effect measurements. A method is also given for measuring the polarizability of polar molecules in a given rotational state. The transition $J=1\ensuremath{\rightarrow}2$, $\ensuremath{\Delta}M=0$ for the ground vibrational state of carbonyl sulfide (OCS) was studied and the electric dipole moment was determined to be (0.7124\ifmmode\pm\else\textpm\fi{}0.0002) Debye units. In addition the polarizability anisotropy (${\ensuremath{\alpha}}_{\mathrm{zz}}\ensuremath{-}{\ensuremath{\alpha}}_{\mathrm{xx}}$) was measured and found to be (2.4\ifmmode\pm\else\textpm\fi{}3.0)\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}24}$ ${\mathrm{cm}}^{3}$.Effects caused by the fourth-order term in the perturbation expansion for the Stark Effect were observed and found to be in good agreement with theoretical predictions.