MILLIMETER AND SUBMILLIMETER SPECTRUM OF DSSD.
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Date
1969
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Ohio State University
Abstract
The millimeter and submillimeter wave spectra of DSSD have been measured using a 6 ft free space cell. DSSD is a very slightly asymmetric top molecule ($K = -0.999992$) and its spectrum shows all the features of a $\bot$-type $transition.^{1}$ The outstanding features of this type of rotational spectrum are the strong Q-branch absorption lines. From the assigned millimeter and submillimeter ground state Q-branch transitions of the $D^{32}S^{32}SD$ species, the band centers for the $^{R}Q_{0}, ^{R}Q_{1}$ and $^{R}Q_{2}$ branches are determined to be: $\begin{array}{l} ^{R}Q_{0}: 69 916.42\pm0.3 Mc/sec (2.332 cm^{-1})\\ ^{R}Q_{1}: 209 737.0 \pm 2.0 Mc/sec (6.996 cm^{-1})\\ ^{R}Q_{2}: 349 540.0 \pm 3.0 Mc/sec (11.659 cm^{-1}) \end{array}$ All transitions originating from the $K \neq 0$ levels show the expected K-type splitting. Because of this and the fact that there is only a small difference between the rotational constants (C-B = -0.29 Mc/sec) the Q-branches have a rather complex structure. A simultaneous analysis of the Q-branch positions shows that the centrifugal distortion treatment with correction terms to $P^{6}$ is not quite sufficient to account for the observed spectra. A similar result was obtained for $HSSH.^{2}$ For the $^{R}Q_{0}$ and $^{R}Q_{1}$branches the measurements were extended to the first excited states (torsional vibrational state $v_{t} = 1$ and the S-S bond stretching vibrational state $v_{o} = 1$). The internal rotational splitting of the ground state as well as the excited states is too small to be resolved, which is in agreement with our observations on HSSH.
Description
Work at Duke University supported by the U.S. Air Force Office of Scientific Research. $^{1}$ G. Winnewisser, M. Winnewisser and W. Gordy, J. Chem. Phys. 49, 3465 (1968). $^{2}$ G. Winnewisser and P. Helminger, Bull. Am. Phys. Soc. II, Vol. 14, No. 4, 622 (1969).
Author Institution: Department of Physics, Duke University; Division of Pure Physics, National Research Council of Canada
Author Institution: Department of Physics, Duke University; Division of Pure Physics, National Research Council of Canada