THE ELECTRIC DIPOLE MOMENT AND THE MOLECULAR QUADRUPOLE MOMENT OF $^{16}O^{12}C^{32}S$ AS MEASURED BY THE MOLECULAR BEAM ELECTRIC RESONANCE METHOD.

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1969

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Ohio State University

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Using the recently constructed electric resonance machine with combined parallel electric and magnetic fields, we measured the J=1,ΔJ=0,Deltamj=±1 transition of OCS. From the measurements at E=800V/cm,H=0 and E=800V/cm,H=8109G we determined the dipole moment1 and the molecular quadrupole moment. The preliminary results are: \begin{eqnarray*} \mu_{vl}& = & 0.71499 \pm 0.00005 D\ Q_{11} & = & -(0.086 \pm 0.07) \times 10^{-26} esu cm^{2}. \end{eqnarray*} The quoted error in the dipole moment is determined by the inaccuracy of the voltage standard (0.003%), the inaccuracy of the spacers (0.003%), the flatness of the C-field plates (better than 1.2×10−5, of the spacer thickness 6.3632(2) mm), the optical contact between C-field plates and spacers, and the precision of the line position determination. A measurement with an interferometer showed that the deviation of the electrode spacing from the thickness of the spacers was less than 0.005%. The line position was determined to within 0.002%. The quoted value of 0.71499 D is in agreement with Muenter's value of 0.71525±0.00020D1,3. We have not yet measured the magnetic field strength within the vacuum chamber and so at present we cannot give the exact values for g1 and x1x1. However, the error in the molecular quadrupole moment is much less influenced by a small change in the magnetic field. The systematic error in the magnetic field strength will be roughly 0.5% or less. An error of +0.5 in this field will result in a shift of the molecular quadrupole moment of −0.04×10−20 esu cm2. We hope to give final results at the symposium.

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1 John S. Muenter, J. Chem. Phys. 48, 4544 (1968). Electric dipole moment of carbonyl sulfide. 2 W. H. Fluggare, W. Huttner, R. L. Shoemaker and P. D. Foster, J. Chem, Phys. 50, 1714 (1969). Magnetic susceptibility anisotropy, molecular quadrupole moment, and the sign of the electric dipole moment in OCS. 3 Instead of Muenter's published value 0.71521 D calculated with h=6.62520×10−27 erg. sec., we give here his value calculated with h=6.62559(16)×10−27 erg, sec. (Rev. Mod. Phys. Oct. 1965, p. 590).


Author Institution: Physical Laboratory University of Nijmegen, Nijmegen, The Netherlands

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