Coherent Raman and Infrared Studies of Sulfur Trioxide |
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Authors: | Engelene T.H. Chrysostom Nicolae Vulpanovici Tony Masiello Jeffrey Barber Joseph W. Nibler Alfons Weber Arthur Maki Thomas A. Blake |
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Affiliation: | aDepartment of Chemistry, Oregon State University, Corvallis, Oregon, 97331-4003;bNational Science Foundation, Arlington, Virginia, 22230;cNational Institute of Standards and Technology, Gaithersburg, Maryland, 20899;d15012 24th Avenue SE, Mill Creek, WA, 98012;ePacific Northwest National Laboratory2, P.O. Box 999, Mail Stop K8-88, Richland, Washington, 99352 |
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Abstract: | High-resolution (0.001 cm−1) coherent anti-Stokes Raman scattering (CARS) was used to observe the Q-branch structure of the IR-inactive ν1 symmetric stretching mode of 32S16O3 and its various 18O isotopomers. The ν1 spectrum of 32S16O3 reveals two intense Q-branches in the region 1065–1067 cm−1, with surprisingly complex vibrational–rotational structure not resolved in earlier studies. Efforts to simulate this with a simple Fermi-resonance model involving ν1 and 2ν4 states do not reproduce the spectral detail, nor do they yield reasonable spectroscopic parameters. A more subtle combination of Fermi resonance and indirect Coriolis interactions with nearby states, 2ν4(1=0, ±2), ν2+ν4(1=±1), 2ν2(1=0), is suspected and a determination of the location of these coupled states by high-resolution infrared measurements is under way. At medium resolution (0.125 cm−1), the infrared spectra reveal Q-branch features from which approximate band origins are estimated for the ν2, ν3, and ν4 fundamental modes of 32S18O3, 32S18O216O, and 32S18O16O2. These and literature data for 32S16O3 are used to calculate force constants for SO3 and a comparison is made with similar values for SO2 and SO. The frequencies and force constants are in excellent agreement with those obtained by Martin in a recent ab initio calculation. |
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Keywords: | Abbreviations: RamanAbbreviations: coherent RamanAbbreviations: CARSAbbreviations: infraredAbbreviations: spectrumAbbreviations: sulfur trioxide |
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