Electric Polarizability Anisotropies of Nitrous Oxide, Propyne, and Carbonyl Sulfide by Microwave Spectroscopy

Very accurate Stark effect measurements were made on rotational transitions of nitrous oxide and propyne-d3. Measurements were made with a microwave spectrometer incorporating a special parallel-plate absorption cell capable of sustaining large magnitude electric fields and of producing very homogeneous fields in the absorption region. Analysis of the data gives an electric polarizability anisotropy of 3.222 ± 0.046 Å3 for nitrous oxide and of 2.7 ± 0.6 Å3 for propyne-d3. The dipole moment of nitrous oxide was determined to be 0.160830 ± 0.000016 D. For propyne-d3, there is evidence for a K dependence of the dipole moment. The determined values for the J = 3 → 4 transition are 0.78780 ± 0.00013 D (K = 0), 0.78765 ± 0.00021 D (K = 2), and 0.78741 ± 0.00014 D (K = 3). Stark effect data reported previously for OCS were reanalyzed using a refined method of statistical analysis and the new molecular beam value for the OCS dipole moment to determine the revised OCS polarizability anisotropy of 4.67 ± 0.16 Å3. In each case, the error limit represents the 95% confidence level calculated in the least-squares analysis, but does not include the uncertainty in the dipole moment value for OCS which was used as a standard in the data reduction.