15min:

JEFFREY BARBER, ENGELENE T. H. CHRYSOSTOM, TONY MASIELLO, JOSEPH W. NIBLER, Department of Chemistry, Oregon State University, Corvallis, OR 97331; ARTHUR MAKI, 15012 24^th 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.

Sulfur trioxide is an important participant in reactions in the upper atmosphere and also in a number of industrial processes. It is a D_3h planar oblate top whose spectroscopy is surprisingly incomplete, in part due to its extreme corrosive properties. We report here a comprehensive investigation of all four fundamental bands of ³²S¹⁶O₃. High resolution (0.001 cm^{- 1}) coherent anti-Stokes Raman scattering (CARS) has been used at Oregon State University to examine the Q-branch structure of the IR-inactive ₁ symmetric stretching mode of ³²S¹⁶O₃. This spectrum reveals two intense Q-branch regions, with complex vibrational-rotational structure. The modeling of this has been challenging and involves a subtle combination of Fermi-resonances, indirect Coriolis interactions, and l-resonances with nearby hidden states; 2 ₄ (l = 0, \pm 2), ₂+ ₄ (l =\pm 1), 2 ₂ (l =0). The analysis of the perturbed ₁ spectrum, achieved by locating these states via high-resolution infrared hot-band studies performed at Pacific Northwest National Laboratory, will be presented in this talk.