15min:

TONY MASIELLO, JEFFREY BARBER, ENGELENE T. H. CHRYSOSTOM, JOSEPH W. NIBLER, Department of Chemistry, Oregon State University, Corvallis, OR 97331; ARTHUR MAKI, 15012 24th Ave. S. E. Mill Creek, WA 98012; ALFONS WEBER, National Science Foundation, Arlington, VA 22230 and National Institute of Standards and Technology, Gaithersburg, MD 20899; THOMAS A. BLAKE, ROBERT L. SAMS, Pacific Northwest National Laboratory, Richland, WA 99352.

We are engaged in a comprehensive investigation of the spectroscopic properties of sulfur trioxide, an important participant in reactions in the upper atmosphere. The fundamental modes and several hot bands of the isotopic variants (³²S¹⁸O₃, ³⁴S¹⁶O₃, and ³⁴S¹⁸O₃) have been investigated using high resolution infrared spectroscopy and coherent anti-Stokes Raman scattering. For all isotopic variants, the Raman-active symmetric stretching mode ₁ shows complex Q-branch patterns due to indirect Coriolis couplings, shape l -resonances, and Fermi resonances with dark ₂, ₄ combination/overtone levels. Essential to modeling the interactions of these levels with ₁ is the understanding of the fundamental vibrations that make up these levels. The analysis of the ₂, ₄ infrared active fundamental vibrations of ³⁴S¹⁸O₃ will be presented, along with efforts to model the complex ₁ CARS spectrum using information derived from studies of hot bands involving ₂ and ₄.